Forretress conceals itself inside its hardened steel shell. The shell is opened when the Pokémon is catching prey, but it does so at such a quick pace that the shell’s inside cannot be seen. It remains immovably rooted to its tree. It scatters pieces of its hard shell to drive its enemies away. It is encased in a steel shell. Its peering eyes are all that can be seen of its mysterious innards.
Pokédex entry #205
Forretress in Pokémon GO
It's possible to hatch Forretress from an egg?
No, Forretress can't be hatched.
Which are Forretress’s strengths and weaknesses?
Forretress is a bug and steel type Pokémon. bug type pokémons are strong against grass, poison, psychic pokémons but weak against fire, fighting, flying, ghost pokémons. steel type pokémons are strong against ice, rock, fairy pokémons but weak against fire, ground, flying pokémons.