Color Change
Changes type to match when hit by a damaging move.
Full effect
Whenever this Pokémon takes damage from a move, the Pokémon's type changes to match the move. If the Pokémon has two types, both are overridden. The Pokémon must directly take damage; for example, moves blocked by a Substitute will not trigger this ability, nor will moves that deal damage indirectly, such as Spikes. This ability takes effect on only the last hit of a multiple-hit attack. In Pokémon Colosseum and XD: Gale of Darkness, this ability does not take effect on Shadow-type moves.
In game description
The Pokémon’s type becomes the type of the move used on it.
Pokemon with Color Change
Using Color Change in Cobblemon
Abilities are passive and always active, so Color Change 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.