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When this Pokémon is poisoned, whether Toxic or regular, it heals 1/8 of its max HP at the end of each turn instead of taking damage.
If this Pokemon is under the effects of Heal Block, it neither loses nor gains HP at the end of the turn.
If a Poison Heal Pokemon is under the effects of Toxic poison, their Toxic counter still increases normally, even though they aren't taking damage. This means that if the Pokemon loses Poison Heal, the Toxic damage it receives is the same as it would be getting on that turn if it hadn't had Poison Heal
This Pokemon still takes poison damage out of battle.