The only Pokémon that can have the ability Wonder Guard is Shedinja. Wonder Guard prevents damage from attacks that are not super effective, giving Shedinja an unusually powerful defensive effect despite its extremely low durability. Because Shedinja has only 1 HP, any successful damaging hit normally knocks it out immediately.
Shedinja’s Bug/Ghost typing determines which attack types can bypass Wonder Guard. Fire, Flying, Rock, Ghost, and Dark moves are super effective against it, while weather, status conditions, entry hazards, and other indirect effects can also defeat it. Its ability therefore creates a distinctive balance: Shedinja can seem invulnerable against an unprepared opponent but is easy to counter with the right tools.
Shedinja is created when Nincada evolves into Ninjask while the player has an empty party slot and an extra Poké Ball. Its name combines “shed” with “ninja,” referencing the hollow cicada-like shell left behind after an insect molts. Spiritomb, Mimikyu, and Ditto can have unusual abilities or battle roles, but none can naturally possess Wonder Guard.