As One Glastrier

Full effect

This Pokémon has the combined effects of Unnerve and Chilling Neigh. Opposing Pokémon cannot eat held Berries while this Pokémon is in battle. Affected Pokémon can still use Bug Bite or Pluck to eat a target's Berry. When this Pokémon knocks out a target, it utters a chilling neigh, which boosts its Attack stat.

In game description

This Ability combines the effects of both Calyrex's Unnerve Ability and Glastrier's Chilling Neigh Ability.

Using As One Glastrier in Cobblemon

Abilities are passive and always active, so As One Glastrier 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.