Pokémon Red and Blue/YMMV

YMMVs that apply to Red and Blue

 * Base Breaker: Just like Lyra from HGSS, Leaf suffers from this. Don't get into a conversation on whether or not she exists in the game universe.
 * Breather Boss: Bruno of the Elite Four can be easily taken out by any decent Psychic type. This was true in later generations as well, but because Psychic Pokemon were no longer Game Breakers players were less likely to have them in their teams.
 * Demonic Spiders: Anything that had Wrap and was faster than your Pokémon was this. All the opponent has to do is use Wrap over and over to prevent you from attacking. (AI players have infinite power points, you don't) This was especially bad with Tentacool and Tentacruel, who could couple it with Poison Sting, doing more damage and potentially losing a Pokémon.
 * Fridge Logic: When you thwart Giovanni's plans to take over Silph Co and use its technology for Team Rocket's fossil operation, he swears revenge. But when you beat him in a gym match, which has nothing to do with Team Rocket, he disbands Team Rocket and leaves you on good terms. The hell?
 * Also...how the hell did no-one remember Giovanni was once a gym leader!?
 * Because only the player character KNOWS who the leader of Team Rocket is? Outside of Team Rocket, anyway.
 * No, the Silph Co. president and his secretary saw him in person, an NPC in Saffron City mentions that they saw the boss of Team Rocket escape in his helicopter, and the guy posted at the start of Viridian Gym later says after you beat Giovanni "Blow me away! GIOVANNI was the Gym Leader here?" like it's a big deal because Giovanni is notorius for something else. It seems most people knew Giovanni as a mob boss but nobody who might have challenged him in the past ever spoke up about him being a Gym Leader.
 * 1. You are always going to be there to stop him, not matter where he is, so if he causes trouble, he'll be stopped if he's not strong enough.
 * 2. He is out of his gym a lot planning stuff for Team Rocket. Also IIRC it was an old man who can't remember what/who Giovanni was/looked like, so it's likely old age is against him mentally.
 * Though that still doesn't explain the guy at the gym, who's not an old man.
 * Game Breaker:
 * The Psychic Type. On top of being an Infinity+1 Element, the move "Psychic."
 * The item duplication glitch in Red & Blue, which makes the game obscenely easy if used on items like Master Balls and Rare Candies (as it nearly always was). It could also be used to allow one to catch Safari Zone Pokemon the normal way. Fixed in Yellow and the remakes.
 * Genius Bonus: The Magikarp line is a reference to a Chinese legend that states that if a carp can jump over the Dragon Gate (believed to be at the top of various waterfalls), it will be transformed into a dragon as a reward. This holds more ground when Snap shows a Magikarp jumping into a waterfall and emerging as a Gyarados.
 * Growing the Beard: Pokemon Yellow actually is a better game than Red and Blue in terms of gameplay, as the majority of bugs, glitches, and imbalances are fixed, and the way is paved for the full beard-growing of the franchise with Gold and Silver.
 * Good Bad Bugs: Missingno., M, Glitch City, the Safari Zone glitch, and the Mew glitch, among many others. These games pushed the Game Boy cartridges to their limit, and the majority of the more famous glitches stem from shortcuts the programmers took in order to be able to fit the game within the relatively tiny amount of memory available. The Missingno and Glitch City bugs are the result of the games having no actual memory protection, so the game would try to create a Pokémon encounter or environment from the wrong sets of data with no fail safe to notice the difference. As a result, it's possible to break the game to ridiculous extremes and still have it keep on trucking through everything. Additionally, a bug lets Psychic Pokémon be super-effective against Ghost instead of being completely ineffective (All Ghosts in Gen I were part Poison). This made Ghost Pokémon rather weak but Psychic Pokémon (like Mewtwo) awesome (see Game Breaker above)
 * Harsher in Hindsight: In the Pewter City Museum, there is a model of the Space Shuttle Columbia, which disintegrated in 2003.
 * Hilarious in Hindsight: A Lass outside of the Rock Tunnel complains that there should be a pink Pokémon with a floral print. Now that Black and White is out.... Given the reported number of unused designs for Pokémon (many would get used later), it could easily have been an In Joke at the time.
 * Nostalgia Filter: There's a fair base of the Pokémon Fan Dumb as well as the spawned Hate Dumb (towards the newer gens) who refuse to admit that there were ever any other Pokémon, or see any flaws in these games. Many of the game's fans are all too willing to overlook the high amount of Game Breaking glitches (that actually don't require some form of strategy guide to trigger), and some hideous imbalances. Not to mention that there's some Fridge Logic involving the people who refuse to admit that there were new games, as by the time they probably got into the series, Gold and Silver were already being developed or released in Japan!
 * Obvious Beta: While not all the glitches were bad, the fact that they were present at all points to a mild version of this trope.
 * And, of course, the REALLY BROKEN versions were Red & Green, released only in Japan. The games released in America were based on the "Blue" release, which actually fixed some bugs and improved the graphics of the original pair.
 * Seinfeld Is Unfunny
 * That One Boss:
 * Brock is a Wake Up Call Boss for those who started with Charmander or Pikachu. In the latter case, Yellow did make Mankey and Nidoran (that eventually learned Double Kick) available to offset this, but they still require some Level Grinding to access the Fighting-type moves. The remakes also made Brock easier by having Charmander learn Metal Claw.
 * Misty and her overpowered Starmie. In the re-release, it is level 21. If you didn't take Bulbasaur, you're in for some power grinding for your whole team. And it's not even as hard as it COULD have been, had it been given a psychic move to match its subtype. All the available grass types are subtyped poison at this point in the game.
 * Not Paras... But then again, the only way to get a Grass-type move on it at that point is with the Bullet Seed TM in the remakes.
 * Erika, because of her over-use of the move Wrap, one of the most obnoxious moves in the first generation. It became a far less troublesome move in later generations.
 * Due to the previously mentioned overpowered Psychic-types and the fact she has a powerhouse of a team in both, Sabrina was a lesson in frustration in the original games. On the other hand, it's entirely possible to accidentally Sequence Break if you couldn't figure out how to get into Saffron and fight her much later than you're expected to, resulting in a somewhat easier battle, especially if you've got Surf.
 * A fast physical attacker was always the best answer, in the original and the remake, due to pure psychic types generally having awful defense. Too bad most of those are fighting types.
 * Unfortunate Implications: Upon arriving in the US, Jynx caught some flak for being a blackface caricature (the intention may have been a ganguro instead, but we're not sure). Its skin was changed from black to purple in later games to avoid problems.
 * Villain Decay: In the Yellow version, Jessie and James are never all that tough to beat (except maybe in the first encounter), but the way in which they speak to you gets progressively sillier with each encounter, that by the last time you face them, they don't even threaten you so much as they casually ask you to not "disturb their boss' meeting."

YMMVs that apply to FireRed and LeafGreen
"Gary: Oh yeah, right. I feel sorry for you. No, really. You're always plodding behind me. So here, I'll give you a little present as a favor. *gives Fame Checker*"
 * They Changed It, Now It Sucks: A common response to the Extended Gameplay and Sevii Islands.
 * Although the Sevii islands may be the Scrappy Level even if you do like the extended playtime.
 * Accidental Innuendo: Ever take a good look at the fountain at Silph Company first floor?
 * Crowning Moment of Heartwarming: After Cerulean City encounter, when you think Gary leaves as usual, THIS happens.


 * Fake Difficulty: For this troper, the way you get National Dex is this. Seriously, sixty Pokémon? First time it's not that bad, but if you are hardcore or have no one to trade to get exclusives past National like Qwilfish or one of the legendary beasts... getting it second or third time is no more fun. It's rather tedious than fun. The worse is that not only you can't receive non-Kanto Pokémon, but also you can't trade them at all without National Pokédex, even if you hack them into such game and then try trading them into a game with National. Fortunately Emerald onwards you get the upgrade automatically after beating game.
 * As long as you haven't been completely neglecting your Pokédex, you don't actually have to do much (if any) trading to get 60, and given how you get the Experience Share at 50, it's fairly likely that you would have at least close to 60 by the time you beat the game. However, this can be annoying given the fact that nowhere in the game does it actually say you need 60 until Professor Oak tells you about it.

YMMVs that apply to both the originals and the remakes

 * Accidental Innuendo: Prof. Oak. He came when he heard beat the Pokémon League.
 * Ekans = snake, Arbok = cobra, Muk = ???
 * Alternate Character Interpretation: In one "interpretation", your rival is the good guy. This does require some big assumptions, though, and doesn't change the fact that he acts like a Jerkass towards you.
 * Breather Boss: Giovanni is rather easy for being the final Gym Leader, since most of his Pokémon are rather slow and all of them have common weaknesses. Or DOUBLE weaknesses.
 * Even more so in Fire Red and Leaf Green, where his strongest Pokemon in the original Red and Blue--Rhydon--was replaced by a Rhyhorn of all things.
 * Ensemble Darkhorse: Brock. Became an Ascended Extra in the anime.
 * Misty even more so. Was made into a major character in the anime and Pokémon Special.
 * Don't forget Blue/Green/Gary. You can't ignore his girth.
 * On the Pokémon side of things, we have Pikachu, Charizard and Mewtwo.
 * Fridge Logic: Mr. Fuji created Mewtwo for Team Rocket, but it escaped from Giovanni. Giovanni, seeing Mewtwo as danger, he tried to get Silph Scope to Ghost-type Pokémon (which are strong against Mewtwo, at least in FRLG) and later Master Ball as a last-effort weapon against Mewtwo. HE WAS TRYING TO SAVE THE WORLD. Or enslave it.
 * It Was His Sled: The fact that Giovanni, the boss of Team Rocket, is all but common knowledge among even lesser fans who have never played the game.
 * As is your rival.
 * Large Ham: Koga. "Fwahahahahahahahahaha!"
 * Lance as well, particularly when he announces the champion you must face after him.
 * Memetic Badass: Both Red and Leaf, actually. More so Red than Leaf, due to him being more well-known. Leaf gets her fair share though, when she's not on Red's level she's usually shown as being the best of the trio in both a playful manner and a battling manner.
 * Memetic Outfit: Red's original outfit. Just try looking for fanart of Red in his new look outside of FRLG artwork, especially HGSS artwork (which is odd when everyone else has their HGSS outfits). That includes his hair. Not even in HGSS artwork do you see him in his new one, despite the fact he is explicitly shown in both his new hair style (overworld sprite) and his new outfit (battle sprite).
 * "Hi. I like shorts! They're comfy and easy to wear!"
 * Moral Event Horizon: Team Rocket as a whole is revealed to have crossed it by killing Pokemon whose souls now reside in Lavender Tower, including Marrowak.
 * Unwinnable by Insanity: Unleash all of your Pokémon. Sell all your Pokéballs. Leave yourself with only one Pokémon who can't use Surf or fly. Then blow all your money on junk that you can't actually use to obtain new Pokémon. Save your game while on Cinnabar. Now you can't win the game! This is one of the few ways to make the game completely unwinnable through legit methods, and back when you could rent this game, it couldn't be uncommon to find a game that had been left with the save-file trapped in Cinnabar.