Magician
Steals the target's held item when the bearer uses a damaging move.
In game description
The Pokémon steals the held item from any target it hits with a move.
Pokemon with Magician
Using Magician in Cobblemon
Abilities are passive and always active, so Magician 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.