Pokémon with this ability cannot have their Defense lowered by other Pokémon.
Pokémon with Big Pecks
|If any of the following Pokémon were introduced before the generation that Big Pecks was introduced in, then it won't apply to them until then.|
As a Hidden Ability
|If any of the following Pokémon were introduced before Generation V, then they will not have Big Pecks as their hidden ability until then.|