Every ability

Weak Armor

If a physical attack hits this Pokémon, Defense is lowered by 1, Speed is raised by 2.

Standard ability
5
Pokémon
Hidden ability
17
Pokémon

In detail

If a physical attack hits this Pokémon, its Defense is lowered by 1 stage and its Speed is raised by 2 stages.

Pokémon that can have it

22

Standard ability5Any one caught or hatched may have it

Hidden ability17Only one with its hidden ability has it