Thermal Exchange
Raises Attack when hit by a Fire-type move. Cannot be burned.
Full effect
Boosts the Attack stat when the Pokémon is hit by a Fire-type move. The Pokémon also cannot be burned.
In game description
Boosts the Attack stat when the Pokémon is hit by a Fire-type move. The Pokémon also cannot be burned.
Pokemon with Thermal Exchange
Using Thermal Exchange in Cobblemon
Abilities are passive and always active, so Thermal Exchange 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.