Poison Heal is an ability typically held by Poison type animals.
In Battle Use
Animals with the Poison Heal ability heal 1/8 of their health while they are inflicted with the Poison status.
This ability may have evolved from animals that were able to ingest poisonous food sources over time. As a result, toxic substances and statuses do not harm the animals with the Poison Heal ability, but rather heals them slowly.