Generation Iii
Natural Cure
Heals upon switching out.
Detailed Effect
This Pokémon is cured of any major status ailment when it is switched out for another Pokémon. If this ability is acquired during battle, the Pokémon is cured upon leaving battle before losing the temporary ability.
Pokémon With Natural Cure
19 canonical Pokémon forms can have this Ability.

Chansey
Staryu 
Starmie
Corsola
Blissey
Celebi
Roselia
Swablu
Altaria
Budew
Roserade
Happiny
Shaymin Land
Phantump
Trevenant
Pawmi 
Pawmo 
Pawmot
Comfey