Camerupt

This Pokémon cannot be frozen. If a Pokémon is frozen and acquires this ability, it will immediately thaw out; this includes when regaining a lost ability upon leaving battle. Overworld: If any Pokémon in the party has this ability, each egg in the party has its hatch counter decreased by 2 (rather than 1) each step cycle, making eggs hatch roughly twice as quickly. This effect does not stack if multiple Pokémon have this ability or flame body.