Slush Rush
During Hail, this Pokémon has double Speed.
In game description
Boosts the Pokémon's Speed stat in snow.
Pokemon with Slush Rush
Using Slush Rush in Cobblemon
Abilities are passive and always active, so Slush Rush 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.