Marowak is the evolved form of a Cubone that has overcome its sadness at the loss of its mother and grown tough. This Pokémon’s tempered and hardened spirit is not easily broken. The bone it holds is its key weapon. It throws the bone skillfully like a boomerang to KO targets. It is small and was originally very weak. Its temperament turned ferocious when it began using bones.
Pokédex entry #105
marowak in Pokémon GO
It's possible to hatch marowak from an egg?
No, marowak can't be hatched.
Which are marowak’s strengths and weaknesses?
marowak is a ground type Pokémon. ground type pokémons are strong against fire, electric, poison, rock, steel pokémons but weak against grass, bug pokémons. They are not affected by flying type pokémons.