Filter

Filter is an ability in Polished Crystal that reduces the damage taken from super effective moves by 25%. This ability is particularly useful for Pokémon that have multiple weaknesses, as it helps to mitigate the damage they would otherwise take from those types.

It's only found on the Jynx line and the Mr.Mime line as well. Mr.Rime does not have this ability in Polished Crystal so you will end up with a new ability if you evolve Mr.Mime instead.