Steadfast
Raises Speed one stage upon flinching.
Full effect
Whenever this Pokémon flinches, its Speed rises one stage.
In game description
The Pokémon's determination boosts its Speed stat every time it flinches.
Pokemon with Steadfast
Using Steadfast in Cobblemon
Abilities are passive and always active, so Steadfast 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.