Merciless

https://vignette.wikia.nocookie.net/pmysteryuniverse/images/4/44/Merciless.png/revision/latest?cb=20190906220836&format=original Merciless is an Ability that ensures critical hits on poisoned opponents.

Effect
If a Pokémon is poisoned, any attack used on it by the Ability's user will always result in a critical hit. This will not occur only if the Pokémon has Battle Armor, Shell Armor, or is under the effects of Lucky Chant.

Pokémon with Merciless

 * Mareanie
 * Toxapex