Dark Aura
Strengthens Dark moves to 1.33× their power for all friendly and opposing Pokémon.
Full effect
Strengthens Dark moves for all friendly and opposing Pokémon.
In game description
Powers up each Pokémon’s Dark-type moves.
Pokemon with Dark Aura
Using Dark Aura in Cobblemon
Abilities are passive and always active, so Dark Aura 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.