Competitive
Raises Special Attack by two stages upon having any stat lowered.
In game description
Boosts the Pokémon's Sp. Atk stat sharply when its stats are lowered by an opposing Pokémon.
Pokemon with Competitive
Using Competitive in Cobblemon
Abilities are passive and always active, so Competitive costs you nothing to run. If it is marked hidden on a species above, expect it to be harder to obtain: servers differ in whether hidden abilities come from breeding, an Ability Patch, or events.
See the Pokedex for which abilities each species can have, and IVs, EVs and breeding for how to actually pass one down.