Its prey is instantaneously frozen stiff by the cold air it exhales from its huge mouth. While they’re in that frozen state, it gobbles them up. Glalie has a body made of rock, which it hardens with an armor of ice. This Pokémon has the ability to freeze moisture in the atmosphere into any shape it desires. It can instantly freeze moisture in the atmosphere. It uses this power to freeze its foes.
Pokédex entry #362
Glalie in Pokémon GO
It's possible to hatch Glalie from an egg?
No, Glalie can't be hatched.