Regenerator (ability)

Regenerator is an Ability introduced in Generation V.

In battle
Regenerator restores ⅓ of the Pokémon's maximum HP upon switching out.

This effect will occur if Regenerator is the Pokémon's Ability in battle when it switches out and is not suppressed; a Pokémon that obtained the Ability with  will restore HP when it switches out, whereas a Pokémon which has Regenerator but has been affected by  will not. doesn't prevent Regenerator from restoring HP.

Outside of battle
Regenerator has no effect outside of battle.