My Little Pony: Friendship Is Magic/Setting Other Species/WMG

Ponies aren't the only inhabitants of Equestria that inspire mysteries. If you have other guesses:

"Shared Universe guesses go here

Pony guesses go here

Guesses about Equestria itself go here

Guesses on Equestrian Culture go here

Science and Magic guesses go here

Dragon guesses go here

Guesses on other species go here"

"Go back to the Main Setting Guesses page here"

"and you can still go back to the Main WMG Page, here"

Griffons and Ponies crossbreed, all Pegasus Ponies are descended from Griffons.
In Mythology, a griffon and a mare can breed to make a Hippogriff. It's not a far stretch to assume it's also possible in this universe, too. Some of the pegasus ponies seen so far have sharper features, longer wings, more pointed ears and almost beak-like mouths. (Case in point: The jock ponies from Sonic Rainboom.) I think this means they have griffon/hippogriff ancestry. Now, following this line of logic, it's possible that all pegasus ponies are descended from intermarrying of griffons and ponies.

Zebras also come in unicorn and pegasus forms, as well as multiple colours.
Zecora is simply a black-and-white earth zebra. If ponies can come in all sorts of colours, there's no reason zebras can't, so in Zecora's home country, there would be zebras with blue and pink stripes, yellow and green stripes, and every colour stripe you can make in flash. Also, some zebras have horns, and others have wings.
 * While the Ponies of Equestria earn their cutie marks, the Zebra foals earn their stripes!

There is actually some circumstantial evidence for this in the show itself. Zecora has a cutie mark, indicating that zebras have some facets in common with ponies. She also has quite an affinity for plants, which is generally an earth pony thing; this suggests she's an earth zebra.
 * This troper always assumed this; showing a winged zebra would be weird without seeing any Earth first, anyway. Zecora is simply a non-european/american(??) pony.


 * There is an African equivalent to the unicorn, the abada, so they may appear. I don't know about winged African horses though.

Horses and ponies are different species.
Everypony, including adults, are called ponies (young ponies are "little ponies"). Mules (Horse/donkey) are shown and mentioned, and Rarity acts as though they are all ugly or bad in some way. The "Yah, mule!" reference suggests mules do mostly manual labor. Unless Rarity and others are racist against biracial ponies, then horses must be different than ponies. This is backed up by the fact that IRL ponies don't talk or use tools.
 * Are you under the impression that "pony" is a synonym for "foal" rather than a class of short horse breeds?
 * Aside from the fact that the terms aren't synonymous, the transformed mouse-horses on the Season 1 finale didn't seem to be entirely sapient. Then again, they were still behaving more-or-less like mice.

Every sentient race follows the same Earth-Air-Magic dynamic as Equestria.
It's been suggested elsewhere on this page that dragons come in different varieties (with Spike being a different breed from the ones we've seen), and it's been posited that "zebra" forms of unicorns and pegasi also exist. This could extend to all the races we've seen, from griffons to bovines to even the Diamond Dogs. It could go something like this. (Warning: Fan Wank ahoy)...

Alternate Concepts
 * Ponies (technicolor): Earth Ponies, Unicorns, Pegasi
 * Ponies (African): Zebras, Abada, Pegasi Aithiopes
 * Ponies (Asian?): Mongolian wild horses, Qilin, Tulpar
 * Griffons: Hieracosphinx, Keythong (yes, the name is real), Standard griffon
 * Dragons: Earth Dragons, Magic Dragons (Spike's breed?), "Standard" dragons
 * Dogs: Diamond Dogs (Earth), Scurvy Dogs (water), Foo Dogs/Blink Dogs (magic), Black Dogs (air), Hellhounds (fire, may need a rename), Cerberus (Alicorn)

Feel free to add more for the varieties of other creatures, or suggest different line-ups.
 * I'd say dragons likely include Water instead of Earth. Steven Magnet, the Sea Serpent is a dragon in this lineup (though Fluttershy doesn't know that Sea Serpents are a dragon subspecies), and we have Water-Magic-Air.
 * Sea serpents might constitute their own group. So far, we've seen the Hydra and Steven Magnet. They might count as the "Earth" and "Magic" varieties, respectively (Steven is pretty magical). Now all we need is a flying sea-serpent…
 * Steven's pretty clearly an Asian-style dragon. Notice how much his emo-fest was stirring up the river? That's actually rather typical.
 * Seeing Spike's adult form in "Secret of My Excess," it is confirmed that Spike will not grow any wings like the other dragons shown so far.
 * I'd call the dogs of the air Canes Majores, after the Ursa Major.
 * There are hippocampi out there, along with the kin of Sleipnir. Count on it.

Magic causes creatures to become an Amazing Technicolor Population.
A wide array of creatures that explicitly make use of magic and/or some supernatural power (ponies, dragons, etc.) have been shown to come in wildly different colors. Meanwhile, creatures that come in "mundane" colors, such as Zecora, are shown to use little to no magic (Zecora gets her "magic" by using various magical plants). Even the Poison Joke, a practically-magical poisonous plant, is pretty vibrant for what is essentially an exotic ivy.

Hippogriffs and other pony/hybrid species exist in the My Little Pony Friendship Is Magic universe.

 * Since we know that mules, a horse-donkey hybrid, exist in the My Little Pony Friendship Is Magic universe, it's not too much of a stretch to assume that other hybrid species exist. Griffins also exist, which could imply the possibility of Interspecies Romance between two non-pony species. In Real Life, there are zebra-horse hybrids, and since zebras exist in the My Little Pony Friendship Is Magic universe it's also no stretch that they could breed with ponies.
 * Or that mules in Equestria aren't bred like mules in our world.

Zebras come in other colors in the My Little Pony Friendship Is Magic universe.

 * Past My Little Pony franchises feature zebras that come in bright colors just like the ponies. Since Zecora is the only zebra we've seen in My Little Pony Friendship Is Magic so far, there's no reason to believe that there are no brightly colored zebras.

Every sentient species have their own Physical God.
Considering that Princess Celestia and Luna are the only Alicorns in series so far, there may be other god-like rulers for each sentient species.
 * Of course, there comes the question of what those would be. Is there an Eastern dragon watching over Spike's ilk? Do the Diamond Dogs answer to the great and mighty Snoop Dog?
 * I laughed at the Snoop Dog part, perhaps he can voice the Diamond Dogs' leader. The buffalo's Physical God could be a white buffalo, considering to be sacred among the plains Indians.

Griffons and ponies are locked in Fantastic Racism, with an angry peace at best and war at worst.
It's a common fandom idea that, if griffons have a civilization, it's against the ponies, and griffon wars tend to factor in the general pony-past, or even the pony-present, in fanworks. It certainly has precedence; in mythology, griffons ate horses, and animosity toward a pony culture would be the closest thing.
 * I'm skeptical about this, at least the modern antagonism between the two cultures, seeing as how Gilda was able to walk around unmolested and her treatment of Ponyville seemed more about how it was a small boring town (she came during a slow week), and she was allowed to attend Junior Speedsters Flight Camp (or Rainbow Dash was... its location isn't quite made clear). I'd say they have a neutral stance in modern times, but they are kept apart because the two cultures freak each other out (which is why Griffons are unrecognized by Pinkie and considered rare by Rarity). Griffons are likely carnivores, but have the same cultural opposition to eating sentient creatures as we would, and pretty much every animal in Equestria qualifies. Meanwhile, because Equestrians are fairly isolationist, they probably wouldn't realize animals outside their lands can't hold conversations. To keep the Griffon/Horse dichotomy, Griffons likely raise (non-sentient) horses, something that is viewed by Ponies like Westerners view eating Great Apes at best (and allows for the existence of phrases like "gift horse" without referring to slavery).
 * It's also possible that Gilda is a Griffin ambassador in Equestria without telling to Rainbow Dash, and just like the bad guy from Lethal Weapon 2, she had diplomatic immunity, and was abusing it.
 * My personal canon is that the Griffon-Pony War ended a few years ago; Gilda is of the first generation to grow up knowing peace. but she still picked up on her parents' quiet animosity towards ponies, and so she hates them as well, with one exception. Meanwhile, Ponyville is in the shadow of Canterlot, the capital city. Since a country usually spreads out from the capital, and I imagine the war was sen mostly at the border between the two counties, it may be that none of them actually saw the war, meaning that it was too distant for them to develop emotional feelings against griffons. I'm not sure where the Young Fliers Camp would be located, but since the war is over they had no reason to bar griffons from joining. Gilda may have gotten some flak from the poinis that came from the border, but Rainbow Dash likely defended her like she did Flutershy at Flight School, which may be why they became friends in the first place. And this suddenly became an impromptu fanfic.

Griffons aren't themselves a race.
Note that Rainbow Dash had to explain to Pinkie Pie just what Gilda was, whereas everyone understands what a dragon is right away. It's possible griffons aren't a race at all, and Gilda is the quintessinal result of a lion and eagle getting familiar, thus a unique creature in Equestria. "I hear she's an old friend of Rainbow Dash; a griffin! So rare!"
 * Possibly supported by Rarity's interest when talking to Applejack at Pinkie's party:


 * We have a griffon in MMMMystery On The Friendship Express, but he's French. Might support the idea that griffons are simply non-natives.

There are other species that use magic.
But they are few and far between, which is why we haven't seen any other species besides unicorns that can directly use and control magic. Magic-using species could include kitsune, eastern dragons, (as they're generally depicted as having a variety of magical abilities) kirins, and perhaps even others. Different species may have different specialties of magic, like kitsune being able to shapeshift.

Mules are Equestria's go to source for migrant labor.
Combine the place of donkeys and mules within stereotypical Mexican culture, the fact that the only mule we saw was on Sweet Apple Acres, and the Real Life migrant work situation in the US.

Zebras do have cutie marks.
However, they are more simplistic than the ones the pony species have. They are the same color as their stripes and they tend to resemble various tribal symbols.
 * Furthermore, unlike ponies, zebras are born with their cutie marks, and so know right away what their lot in life shall be.

The Ponies raise pigs to feed their carnivorous pets with.
The Ponies have been shown to own dogs, cats, and even aligators, and they must eat something. It's just strange to imagine a butcher pony.
 * It's why Fluttershy is so timid.
 * Fluttershy did feed fish to Ferrets.
 * According to Word of God, ponies really like truffles, enough to provide free room & board. Cows aren't so lucky.
 * Wait, aren't truffles just fungi?
 * The cows are there because the ponies use milk.
 * Presumably the same thing can be said for the chickens, although that raises the question of weither ponies can consume eggs. They must use them in baking.
 * In one episode, Pinkie gives Spike a quiche. Quiches need eggs, so yes, ponies eat eggs.
 * Presumably they also raise chickens for feathers, since we see that they have pillows.
 * And now it's been confirmed that ponies definitely eat eggs.

For an animal, to become a pet is the greatest honor one can be bestowed.
Despite being taken care of by the ponies, wild animals still live without names, without homes, and often, without real respect from the ponies. To be a pet, however, is to get all of that and more. You recieve a name, which ponies use to distinguish you from every other often-identical member of your species; you recieve a comfortable home; and best of all, you get a pony who respects you, not as an animal, but as a friend. That's why Rainbow Dash's test was such a big deal for those animals, especially the tortoise: it's a chance to be somebody for somepony, not just another face in the forest.

Pigs are nonsentient
Unlike all the other animals with hooves on the show, pigs are the only creatures who actually act like normal pigs. Most of the other animals with hooves, which are buffalo, cows, donkeys, sheep, Zecora the zebra, that one mule, and of course ponies, are all capable of speech with cows and sheep probably knowing they are merely livestock to the pony race in a mutually beneficial relationship and lampshading it whenever possible. The goats working for Iron Will, on the other hand, despite not talking are shown to be at least intelligent enough to function as normal people within pony society with Iron Will one the few people that can translate goat speak.

Pigs, however, whenever they are shown do not talk at all and act like pigs in the real world, except a bit more friendlier. This may have something to do with the omnivorous nature of pigs as the only hooved creatures that can survive purely on meat.
 * Before anyone points it out, yes ponies have been shown to eat eggs. This mostly comes from the probable higher protein and nutrition requirements magical ponies need and they don't technically count was meet since the eggs are unfertilized.
 * How do you explain the diamond dogs? They're as sapient (sentience is merely being conscious) as ponies, but they're dogs and thus, more carnivorous. Not to mention dragons. I don't see too much of a co-relation between a creature's diet and how sapient a creature is.
 * I'm talking about animals WITH HOOVES. I even said so in the first sentence!

The Poison Joke in Bridle Gossip came from Discord.
They were one of his past crimes. After he was put in his stone prison, the Canterlot citizens got rid of the Poison Joke, except in places where ponies are not found. Like the Everfree Forest!

The Everfree Forest came from Discord.
When Discord was defeated by Celestia and Luna, he left a parting gift: a seed/curse/his other tooth. It did nothing at first, but when the time was right, this gift exploded into a mass of plant matter. The sisters' magic, the Royal Guards, and even the pony folk could do nothing to stop it, and things only got worse when terrifying monsters came with the greenery. Eventually, the grand metropolis of Everfree was abandoned, and left to its own devices, grew into the massive shrine to pony-free chaos that is the Everfree Forest.

The origin of Zap Apples
They are stated to be unlike any other apples seen due to their magical nature. And the color of the apples and the way in which the growth cycle happens to look a little bit familiar. The creation of a brand new magical fruit would be a pretty good way to get into legends, while the extremely small time frame to collect them could cause some doubt in the story.

Rocks are edible
We know Pinkie's got an Iron Stomach, with her ability to eat spicy food and burnt food, who's to say she didn't get it eating rocks on her family's rock farm?

In the FIM universe, gems grow like plants.
There's a lot of evidence to suggest this. One, gems seem to be in GREAT abundance. Still considered valuable (likely for their beauty, and from what we've seen, some gems are rarer than others) but Rarity can obtain them easily enough to cover her designs in them. There are apparently plenty buried just a few inches under ground. No one has a problem with Spike or other dragons eating gems, and Mr. and Mrs. Cake even made him a cupcake covered in Sapphires. Considering that dragons seem to subsist heavily on gems, there's likely some replenishing source. During "The Secret of My Excess", Spike mentions aging a Fire Ruby for months, which implies putting some control over it's qualities like size. Then, in "The Super Speedy Cider Squeezy 6000", Spike makes a reference to "sapphire season", which implies a certain time of the year when it's best to get sapphires. How would that be possible if sapphires didn't grow or replenish in some way?
 * If this is canon, then the rock farm in Pinkie Pie's flashback would finally make sense. Maybe all mineral formations grow like plants. We've already seen that nature in Equestria doesn't work like it does in our world, after all.

The Seeds of Truth only bloom when someone confesses their lie.
It won't bloom simply by stating a fact. Applejack rarely lies, and at the time the Seeds were planted, she had nothing that needed confessing.
 * Which raises the question: just how many corn-cakes did Pinkie eat?
 * More than six.
 * 40 cakes. That's as many as four tens.
 * And That's Terrible.
 * All the corn-cakes. All of them.

The Cockatrice from "The Stare Master" was originally from Fluttershy's place.
Since she keeps chickens and an assortment of other animals, it wouldn't be a huge streach if she had a rooster, that managed to lay an egg, which then happened to be incubated by a toad. The cockatrice was hatched from the egg and then left to live in the Everfree Forest.
 * I think it would be a pretty big stretch for one of her roosters to have laid an egg.
 * No offense, but doesn't a chicken egg hatched beneath a toad make a basilisk?
 * No offense taken, but roosters are male. They don't lay eggs.
 * That's the whole point. A rooster laying an egg would be EXTREMELY rare. Otherwise, cockatrice would be more common.
 * Not really. A basilisk is born from a snake or toad egg hatched beneath a rooster. The reverse of a cockatrice basically.

Parasprites were created to end predation.
They're a nonsentient or minimally sentient food source for carnivores. Take a pound of vegetables, set a parasprite on it, wait a few minutes, and you have a pound of meat with practically zero waste... that was the idea, anyway.

Parasprites hibernate.
If they didn't, the first outbreak ever would've been the last; they'd have stripped the continent and starved or been wiped out trying. The one that came to Fluttershy may have lain buried for hundreds or thousands of years; it may have been a lone survivor, or it may have been an early riser from a still-sleeping swarm.
 * It's been mentioned that Parasprites may be native to the Everfree forest, where they're the prey to just about everything in there. The Ursa Major alone could probably eat several hundred thousand in one night (that is, if they ate Parasprites). And so began a bizarre cycle: everything eats Parasprites, so they became explosive breeders to adapt.

Parasprites spell doom, but not (just) for the obvious reasons.
Outside Celestia's protection, creatures do what they have to to protect themselves. Dragons depend on the food chain like anyone, so when something threatens it, they don't take chances.

A Draconequus is the result of a pony and a dragon loving each other very much.
When Discord's species is mentioned, one of the first things said about him is that he has the head of a pony and the body of a dragon. Perhaps his parents were a dragon and a pony?
 * Oh God Spike/Rarity's children!
 * Discord is the son of Spike & Rarity....from the future, who traveled to the ancient past and was imprisoned for his mischief.
 * Why does this make so much sense?
 * No it doesn't. It makes absolutely no sense. Which is why it's perfect for Discord.
 * Makes perfect sense if he was raised by PINKIE PIE!!!! but never really learned any morals from her.
 * Mind Screw!

Discord is the draconequus equivalent of Celestia and Luna.
The Princess' are a combination of traits of all three types of ponies, and are extremely powerful compared to any one of them as a result. Discord is a combination of all types of ponies, as well as all types of dragons, making him correspondingly more powerful. At some point in time, we'll see a non-evil draconequus with normal levels of power.

Music has no effect on parasprites.
Possible explanations for what happened:
 * (1) Pinkie was in amoral-trickster-goddess mode and concealing her powers in the most needlessly elaborate way possible.
 * (2) They were a Magic Feather that she didn't know she didn't need.
 * (3) Music helps her focus her powers. Usually just singing as she works is enough, but a mass mind control spell needs something more.

The Windigos came from Discord.
Discord created them to spread chaos, naturally.
 * How could they create chaos if everypony was frozen solid? I think Discord wouldn't like that.

The Changelings have a translation error.
When they say "love" they mean "blood". So they feed on blood. That's what the fangs are for.
 * One day, the Changeling Queen heard the word "love" from a pony and asked what it meant. The reply was some poppycock about "it makes you feel all warm inside", "you need it to live", and "it comes from the heart", which she took the wrong way.

Changelings have been around for the entire series.
They've just been mimicking normal ponies the entire time, and done nothing to draw attention to themselves. Any of the background ponies could be changelings.
 * Holy mother of Celestia.
 * It gets better. You know all those duplicate assets Studio B uses for crowd shots? So they can fill out a scene with identical ponies to save time? Are those supposed to be there?
 * Better yet. Now we know why Bon Bon's voice is different every time. Each appearance is a different Changeling taking her form.
 * I'm Lyra Heartstings, yes I'm the real Heartstings, all the other Lyra's are changelings imitating, so will the real Lyra Heartstrings please stand up, please stand up, please stand up?
 * The Jerkass ponies in "Putting Your Hoof Down" may have been Changelings all along!
 * There is no proof that mook changelings can also mimic voices
 * When Twilight Sparkle said "They're Changelings, remember?" just before the brawl with the Changelings, many of the Changelings taking Twilight's form repeated the phrase in her voice.
 * Underped Derpy.

Changelings are actually the largest minority in Equestria.
But most of them are law abiding citizens that just use their shape shifting powers to fit it. Since they only feed off of the love that their friends and family feel towards them, they don't really draw attention to themselves.

Everypony is a Changeling.
But some of the them have become the mask.

The Changelings are actually what remains of the Flutter Ponies, after their race was twisted by some horrible curse.
Despite their obviously monstrous nature, they still bear many basic similarities to ponies, and have insectile qualities and comparative magic as well. It's possible they were once ponies themselves who were... changed... by something. Perhaps they are all that remain of Flutter Ponies in modern-day Equestria?
 * Maybe the Queen was an attempt by the Flutter Ponies to create a Celestia-analogue, powered by the Power of Love. It didn't end well.
 * Maybe they're the Unseelie to the flutter ponies' Seelie court?

The Changelings ATE the Flutter ponies.
Which is why there aren't any in the FiM setting. They also ate the seaponies. The reason that the Queen didn't kill Cadence or Twilight is because she didn't want to run out of ponies again.

The Changelings first made their appearance in Story of the Blanks.
You know... As the residents of Sunny Town?
 * How did they get the wings?

The Changelings are blanks that escaped
They where twisted in a different way then those who became blanks.

Changelings can feed on familial and platonic love, not just romantic love.
Queen Chrysalis was able to defeat Princess Celestia because she was drawing power not only from Shining Armor's love for his fiancée, but also from Princess Celestia's love for her niece.
 * Implied since when confronted with the mane six, they turned into copies of them.
 * Wasn't that just so they wouldn't know who was who?

Changelings are aliens.
That's why nopony but Cadence knows about them (Cadence only knows from Chrysalis herself, being her first victim). Their nature allows them to travel through space with no need for spacecraft (like the Zerg Swarm, for example). They invade every inhabited, advanced planet they encounter, feast on the emotions of the locals while wreaking chaos, and leave after slaughtering the whole population, off to the next world. Shining Armor and Cadence's spell didn't just blow them out of Canterlot and Equestria - it blasted them all the way off into space.

They look superficially like ponies for the same reason why many aliens in most media look at least partially humanoid. They know Equestria's language because of either some kind of telepathy, or because the Queen has been masquerading as a pony and preparing the invasion long enough to learn it (the other Changelings may not even know it at all, the only time they speak, they just imitate the sound of Twilight Sparkle's voice).

Chrysalis is not the only Changeling Queen.
She rules only one single Hive out of potentially many more.

Chrysalis was killed on impact after being thrown out of Canterlot or by the force of the blow itself
Chrysalis was hit with enough force to send her sailing out of Canterlot at extremely high speeds. Either she was mortally wounded by the impact itself, or hit the ground far in the distance at near super sonic speeds in an uncontrolled landing.

Chrysalis was NOT killed on impact and will be returning for revenge!
Come on, Team Rocket survives this kind of fall every week. And Queen Chrysalis has wings! She will definitely be coming back for another round, and this time she will be smarter and harder to unmask.

Chrysalis was NOT killed on impact, but will NOT be returning for revenge.
It's the Queen's duty to provide food for the swarm. She may have failed to give the swarm Canterlot, but she'll still give them food.

The threat made against Canterlot that Shining Armor mentioned was NOT made by Chrysalis.
She isn't the type that openly announces her coming. Also, without the threat, the Force Field wouldn't have been there in the first place. Making a threat so Shining Armor raises a force field, then controlling him and draining his love so that he drops it again doesn't make a lot of sense. She discovered Equestria as a source of energy just coincidentally at the same time someone entirely else made a threat to Canterlot. That's why she had to control Shining Armor in the first place.
 * There are a lot of holes in this theory. It implies that she made the threat with the intention of him raising the shield, but that could have been an unforeseen possibility on her part.

The Changelings came from another dimension.
Specifically, a parasitic dimension where time doesn't flow normally and space is in a constant flux. This dimension "attaches" itself to others and feeds off the emotions, lifeforce and other energies until it is no more then a husk. Then it moves onward.

The Changelings take on the basic shape of the most dominant life-form when visiting new worlds.
They looked like ponies in this case, but had they visited the human world, they would look more human-like.

The Changelings come in millions of varieties, all able to copy the appearance of what it looks like.
That is, there are the basic pony-Changelings, then griffon-Changelings, dragon-Changelings, Changelings for most species of animal, etc. Their eventual goal is to replace every living thing on Earth.

The Changelings and the alicorns share a common ancestor.
Mostly because all the Changelings had horns and wings, not just their Queen. Maybe Changelings are "fallen" alicorns, or their equivalent of demons?

The Changelings are just that
Snatching foals and replacing them with their own offspring (or possibly full-grown changelings) is their usual MO - overt action like in the episode happens rarely. This wasn't mentioned because the intended audience would never have slept again.
 * Perhaps Celestia put a stop to the practice. Would explain why they resorted to such drastic measures.

Queen Chrysalis was once an alicorn
She has the same basic bodytype as the rest of the princess ponies. Perhaps Queen Chrysalis took over and corrupted one.
 * Alternatively, she was an alicorn that was corrupted by the same evil force that turned Princess Luna into Nightmare Moon.

If Chrysalis returns, she'll no longer have her swarm and her goal will be to rebuild it
When she was last seen, her Changelings were hurled in all directions at super sonic speeds. Her swarm has been scattered to the winds and she can't reform it. So she comes back, assumes a different form, and tries to get enough love energy to begin reproducing like an insect queen to rebuild it. This may involve an Alien Shout-Out, with her transforming into a form resembling a Xenomorph Queen.
 * Additionally, parts of her swarm will no longer be loyal to her, leading to a possible Enemy Civil War and some changelings joining the Equestrians.

Magic fueled by The Power of Love and The Power of Friendship can't be consumed by Changelings.
As shown in the end, they were effected by the Heart Beat-Down Cadence and Shining Armor laid on them. When channeled into a magical weapon like the Elements and the attack that defeated them, it's changed in such a way that they can no longer absorb it. Think of it like a human and water. Humans can drink fresh water and must do so to survive, but drinking salt water is detrimental to our health. Magic fueled by Love is essentially the same thing to Changelings.
 * I figured they can only consume love that they intercept by shapechanging into the proper recipient.
 * I argue that it would like trying to drink from riot control water cannon as it's blasting you in the face.

Chrysalis is already back by the end of the episode.
She's impersonating Princess Luna, who was in fact fighting the Changelings off screen but was overpowered as well. So the 'Luna' we see arriving for the real wedding and innocently asking whether she's missed anything is in fact just Chrysalis in a new mask...
 * Seems unlikely. Only two things have defeated Celestia in a stand-up fight that we know of - Chrysalis, who could only do so because she'd temporarily tapped into the power of True Love, and Luna. Luna/NMM may well have gotten a boost from her rage and misery, but it still stretches belief to have a bunch of malnourished changeling grunts and their just-got-curb-stomped queen defeat the Princess of Night.
 * Well, that's why it's a Wild Mass Guess. But remember, there are signs that Luna may be spending the day outside Canterlot; a sufficient number of minions zerg rushing her when she's alone could potentially overwhelm her (especially if they caught her asleep), and since that Changeling detachment would have been outside the city when Shining Armor's spell kicked back in they'd never have been affected by it either. And of course most assumptions about just how cosmically badass the royal princesses really are in actual combat are only fanon; that the powerup Chrysalis gets from feeding on the love of a single (albeit exceptional) pony for another apparently makes the difference between victory and defeat in this one canon example where we actually see Celestia fight kind of speaks volumes.
 * Keep in mind it's that very same Love that chucked the entire Changeling army out of the country, so it's not anything to be scoffed at.
 * Technically it was Shining Armor's spell that did that -- just as it's presumably supposed to. He just couldn't have cast it without Cadence's help at that point because he didn't have any reserves of his own left to tap into. (Incidentally, it'd be interesting to learn more about how the Changelings' whole "feeding on love" shtick even works, seeing how the show never actually goes into any detail regarding the mechanics of it. For one thing, Shining Armor doesn't really seem to love Cadence any less when he finally snaps out of his trance, he's simply out of magic...possibly suggesting that that could be what the Changelings are really after.)

Changelings feed on the magic of love, not the emotion.
Consider: Friendship, and by extension love, is magic, right? Well...that means that friends and lovers regularly (and for the most part probably unconsciously, simply by reflex) exchange actual magical energy with each other, and it's likely this exchange that justifies The Power of Friendship and/or Love in the setting. Enter the Changelings, who can metabolize exactly this form of magic (but not automatically others, which explains why Shining Armor's shield and Twilight's magical bolts affected them normally) by intercepting the 'friendship beam' without giving anything back in return and quite likely even have the ability to tease more power out of a suitable 'donor' than they would normally readily send out on their own...

Crashing the Wedding was the changelings' plan, but it wasn't just for a quick nip.
Consider the following; The Changelings have been planning this for a damn long time, scouts have been taking quick nips at Equestria here and there, but not enough for the entire race. So the Queen makes an executive call and they start to put a plan together. Princess Cadence is planning a high profile wedding with Shining Armor, captain of the guard, so they abduct her, and use their love for each other to stage a massive invasion, with the Queen being placed on the inside as Cadance and the shapeshifter troops gathering. But it wasn't enough just to screw around and feed off the chaos of the attack, when they can best feed off sustainable emotions of the strongest variety.

Changelings can turn ponies into more changelings.
Drain somepony of all their love, and they become another loveless monstrosity. Because it would be cool if it worked that way.

Changelings used to be subjects of Princess Luna.
Way back in the backstory, Luna turned into Nightmare Moon because she felt she wasn't getting enough love. What if she needed that love for more than just herself?

After Nightmare Moon's defeat at the hooves of Celestia, the changelings fled Equestria to find new sources of love. As they went centuries without making any real trouble, the mortal inhabitants of Equestria came to think of them as just legends, and Celestia thought that they were not a threat without Nightmare Moon/Luna to lead them, or even that they had gone extinct. After a millennium of fending for themselves, changeling society and possible even biology changed enough to account for any unfamiliarity Celestia may have had with them.

Possible reasons for why they didn't rejoin Luna-
 * After a thousand years, the changelings no longer remembered that they once served her.
 * A feeling of betrayal and abandonment after the Nightmare Moon incident.
 * If Luna and Celestia thought that the changelings had died out, than Luna might not have tried to find them.
 * The Queen preferred working for herself.

If Queen Chrysalis returns, it will be Celestia's turn to kick her flank
Chrysalis outright says the only reason she won is because she'd gotten that power up. She'll already have expended it by the next time she appears and Celestia, still fuming from what Chrysalis did to her little ponies before, will show what would've happened if Chrysalis hadn't had that power up.

Ponies that have been drained too much turn into Zombies.
Sorry Spike, zombie ponies are looking more and more likely. Better find a shotgun or work on your fire breath.

A changeling will become a new Mare-Do-Well.
She'll be under the impression that the original was another changeling herself. Bonus points if she outs herself as a changeling and starts calling herself the Martian Marehunter.

For most of the series, the Changelings were trapped in Tartaros.
But then Cerberus ran away in "It's About Time"...just long enough for at least one swarm to slip out. Nobody noticed their escape at the time because (a) there are no guards in Tartaros itself (the inmates are too dangerous), (b) they're shapeshifters, and (c) they didn't go on a rampage straight away the way some other escapees might have, so when they suddenly attacked Canterlot they came out of the left field for everypony.

Changelings can only impersonate living ponies.
Chrysalis left Cadence alive only because she needed her alive in order to adopt her form - otherwise, it would be a pretty silly move. She also left Twilight alive, so that a changeling could copy her and hence insert itself into Celestia's trusted circle.

Queen Chrysalis DID make the threat, because it's exactly what she needed.
Shining Armor is not just a trained captain of the royal guard, but also the most powerful Barrier Warrior in Canterlot, if not all of Equestria. You'd think someone with defense magic of that power would be capable of protecting himself from mind control. Posing as his fiancee would add an oportunity, but a lot could still go wrong. She first made the threat so that he'd overexert himself maintaining the barrier, weakening him to the point she could control him. This also fixed the problem of Celestia and Luna. Even with The Power of Love there was no gurantee she'd be able to defeat Celestia, much less both her and Luna at the same time. The threat put them on guard, leaving them with 12 hour vigil shifts, as we saw them swap at one point, while trying to get in sleep and basic functions of their job in the process. This removes Luna from the fight, and leaves Celestia at less then full power. The attack would be more unexpected without the threat, but making an announcement allowed her to stack the deck much more firmly in her favor.

A good Changeling will eventually join the mane cast.
The episode that introduces him/her will play out like Zecoras introduction episode but the Aesop will not be "don't judge the appearance" but instead it will be "don't judge someone based off of what others do."
 * And he will be named William.

Changelings are either symbiotic, or parasited.
Those cheese legs are not just for show. They look awfully like moth-eaten clothing, don't they? Changelings are infested with a species of worms, perhaps granting them their shapeshifting powers as a symbiotic tradeoff. Maybe the worms eat their flesh and Changelings depend on eating love to regenerate, or maybe the worms themselves feed on love... but perhaps can resort to eating flesh if left unfed for too long...

The last race targeted by the changelings were humans.
Cadence!Chrysalis compared Pinkie Pie's decoration of the reception to that of a "six year old's birthday party" although horses are adults at six, and this seems to be true for Equestrian ponies (Pipsqueak being under a year old, the Cake twins running, flying and doing magic within a month). Now what kind of animal is still a juvenile at that age?

Chrysalis may have been ignorant of the maturity rate of the ponies of Equestria and assumed it to be the same as the last sprawling intelligent species her kind drained dry.

Chrysalis was planning to turn Celestia into another changeling queen.
She was keeping her in a pupa, which is what contains a young insect metamorphosing into its adult form. Chrysalis may have done this so she could send Celestia out to start another colony to infest another land and repeat the cycle.

Chrysalis didn't get her power from Shining Armor's love
It doesn't seem likely that his love would be strong enough to beat Princess Celestia. His love is just one aspect of him, and altogether he's weaker than her. She got her power from all the bronies that love her.

Chrysalis won
This video says it all.

Changelings can only feed off the love of living beings.
The magic of love needs to be a mutual bond, not an one way love of one being has to a deceased one. They can put mind control spells and bend the rules, but they cannot create fake love or love of the dead. That is why the Changeling queen allowed the let the princess to live.

Now that the changelings have been driven out of Equestria, we won't see any more duplicate background ponies.
Or maybe not. Perhaps not ALL changelings were driven out of Equestria, only Chrysalis' invading swarm.

Chrysalis' hive was starving by the time they arrived in Equestria.
This explains why the Queen's plan was a bit rushed. Her swarm had already failed to conquer several countries, and was dying of hunger. The invasion was a desperation move to stop the Changelings from dying out. She had to go for the largest city - Canterlot - to find enough prey to feed the whole swarm, but she had very limited time. That's why she didn't take the time to learn Cadence's personality better and instead relied on brute brainwashing to keep Shining Armor under control. And yes - that means all the changelings have died of hunger after they were expulsed from Equestria.

Changelings don't really look anything like ponies.
Their basic form is an amorphous mass of black rotten flesh. However, each time they attack a race they shape their bodies into a basic likeness of that race, because having the basic frame ready makes imitation of specific members of the race faster and easier. That means, had they attacked Earth, changelings would have looked like black insect-winged human zombies.

Changelings are the reason that alicorns are so rare.
Long ago, the alicorns were once as numerous as the pegasi, unicorns and earth ponies. One fateful day an alicorn mare had fallen in love with a stallion who was already taken. Using her powerful magic, she secretly kidnapped the other mare and used her magic to assume her form, fueling the spell with the stallion's love for her. The wickedness in her heart corrupted her true alicorn form into the first changeling queen. The kidnapped mare, now drained of all love in her heart, became the first changeling soldier, and the stallion she had deceived became the first changeling drone. Forever stuck as twisted perversions of ponies, the changelings used their powers to assume the forms of other alicorn couples, draining them of their love and turning them into more changeling soldiers. As their numbers grew, they quickly evolved to create cocoons for storing their "food" and future changelings in. In very little time, most of the alicorn population had been transformed into changelings, but only those who weren't of royalty- the changeling queen of the time figured that royal alicorns, such as Princess Celestia, were too risky to attempt assimilation upon, and so they went into hiding to wait for a golden opportunity to strike.

There ARE humans in Equestria, but...
They are cavemen proto-humans. They aren't smart enough to utilize the tools around them, They also have a natural fear instinct of anything they do not understand and live in the "wastelands" where nopony goes anyway.
 * Alternatively, humans are at a similarly advanced as ponykind, but the two species keep separate due to mutual racial tension. (Perhaps they've waged war on each other in the past, and the odd mixtures of technology and fairy-tale magic are inevitable cultural osmosis?)

Humans and ponies both coexist on Earth in the future.
After ponies became an intelligent species due to science, they were kept for scientific experiments for a while, and some were used as unpaid servants. After the Supreme Court ruled that ponies were free American citizens, they lived that way for a while, but many were not happy. Thus, some land was purchased and was offered to the ponies as a place to live free of human society. Some ponies accepted, and Equestria was born. It still contains some elements of the world that spawned it, as the ponies learned everything about civilization from humans. They replicated various great cities and structures, such as the Statue of Liberty, but with a pony theme of course. The ponies also do some trade with the outside world, but not much. For example, in Episode 15, Twilight is clearly using present-day equipment to run tests on Pinkie Pie, but most technology can be replaced by magic, which the ponies were created with, and still maintain the ability to use. As new intelligent species are created (like the smart buffalo, dragons, or smart zebras), some move to Equestria, which can lead to a lot of tension before they are accepted into society. The Everfree Forest is simply a boundary that was planted to separate the rest of the world from Equestria, and part of the original deal was that they weren't allowed to manipulate it, or any area past it, with magic. All ponies are still aware of humans, but most don't know just how dominant they are, assuming they are just another of the intelligent races, which explains why humans haven't been mentioned. There, we have a reasonable, but non-scary, origin story.

There are humans
But they aren't allowed to visit because the human to pony scale is the same as the human to pony toy scale.
 * Or it's the other way around. Because that would be funny.

What really happened to the humans
Humans and ponies once coexisted, but then one pony accidentally discovered how delicious they were. The ponies soon ate up most of them, and the rest fled. Every once in a while, a human will be sent back to see if it's safe, and the ponies will capture them and make them into cupcakes, muffins, etc.

Minotaurs are half Human!
When I first saw the character Iron Will, I noticed he was bipedal but didn't really think much of it, and just assumed he was a bull. However, the characters specifically refer to him as a Minotaur. Minotaurs are by definition half bull, and half Human. Iron Will therefore implies the existence of Human beings in the Equestrian world. I suppose it's possible that in their world a Minotaur is simply a humanoid bull and that they could still have no knowledge of Humanity. But Griffons exist, and Rainbow Dash clearly defines a Griffon as being half eagle and half lion. Since Griffons remain true to their mythological roots, then why not Minotaurs?
 * Then that means the reason they called him a monster is because he's half human
 * If Iron Will is half Human, his father might have been Jordan Chase.

Humans exist but we'll never see them
I'm presuming that humans and ponies exist separate from each other, similar to G1. Humans aren't fictional but they're non-magical and simply don't live near the fantastical animals.

All advanced technology is imported from humans
Ponies are magical, but not that scientifically advanced. Humans can't use magic and developed science more rapidly. We never see them because they live on another continent, but some ponies like human technology and have it imported. For example Vinyl Scratch's turntable and speakers.