Plot Pants

Wardrobe changes bring variety and color to a show's characters, especially in and animated work where the characters have a default costume that they use all the time. These new clothes accompany downtime in an ongoing story arc, when characters are relaxing, playing or fooling around. However, no matter how welcome costume changes are they simply can't stay. When the chips are down and the plot gets moving again, our heroes put their Plot Pants back on and get into the action.

Not to be confused with Magic Pants.

Comic Books

 * Comic Book Superheroes obviously do this: their Secret Identity civilian clothes often aren't the same every time you see them.

Anime and Manga

 * Hayao Miyazaki's Future Boy Conan had its characters change out of their wardrobes when the plot stopped moving, but every time something interesting happens they jump back into their old, ragged clothes as fast as they can.
 * In the manga Edward Elric wears different clothes on occasion when he's not running around being the Fullmetal Alchemist, but when something important happens he's usually wearing his customary black clothing and red jacket.
 * Glaringly inverted in Hime Chen! Otogi Chikku Idol Lilpri. The costume changing Magic Idol Singers wear a different outfit every time they transform but wear the same exact outfits when they're not.

Live Action TV

 * Very rarely, officers on Star Trek will get out of their uniforms when off duty. Especially when on shore leave, or if we have occasion to catch them going to bed.
 * In the Live Action Movie Ben 10 Race Against Time, Ben wears assorted clothes throughout the first chunk of the movie. Once it's hero time, though, he changes into the same white shirt with black highlights that he wore all throughout the original series.

Western Animation

 * Kim Possible and Ron Stoppable alternate between hip, casual clothes at school and home, and their mission fatigues when out saving the world.
 * The Dojo kids on Get Ed normally wear a basic set of clothing, switching to power-up gear (complete with helmets and padding) to do their deliveries or fight Bedlam. However, in one episode they decide to go clubbing and switch to civilian outfits (which are, in fact, Palette Swaps of their regular models - not one polygon has changed).