Immunity
Gen IIIThis Pokémon cannot be poisoned. This includes bad poison. If a Pokémon is poisoned and acquires this ability, its poison is healed; this includes when regaining a lost ability upon leaving battle.
Immunity in Battle
Immunity completely prevents the Pokemon from being poisoned, including both regular poison and the more dangerous badly poisoned (Toxic) status. Any move or ability that would inflict poison simply fails against a Pokemon with Immunity. This also means Toxic Spikes have no effect when a Pokemon with Immunity switches in.
If a Pokemon somehow acquires Immunity while already poisoned — such as through Skill Swap or Trace — the poison is immediately cured. The same applies when a Pokemon regains Immunity upon leaving battle after having it suppressed. This makes Immunity one of the most reliable status-prevention abilities in the game, as there are no workarounds or edge cases that bypass it. Introduced in Generation III, Immunity is found on only 3 Pokemon: Snorlax (as a Hidden Ability), Zangoose, and Gligar — all Pokemon whose design or lore suggests exceptional physical resilience.
