Illuminate
Doubles the wild encounter rate.
Full effect
Overworld: If the lead Pokémon has this ability, the wild encounter rate is doubled. This ability has no effect in battle.
In game description
By illuminating its surroundings, the Pokémon prevents its accuracy from being lowered.
Pokemon with Illuminate
Using Illuminate in Cobblemon
Abilities are passive and always active, so Illuminate 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.