Grumpig uses the black pearls on its body to wield its fantastic powers. When it is doing so, it dances bizarrely. This Pokémon’s black pearls are valuable as works of art. It uses black pearls to amplify its psychic power. It does an odd dance to gain control over foes. It uses black pearls to amplify its psychic power. It does a strange dance to control foes’ minds.
Pokédex entry #326
Grumpig in Pokémon GO
It's possible to hatch Grumpig from an egg?
No, Grumpig can't be hatched.