Inside SHELGON’s armor-like shell, cells are in the midst of transformation to create an entirely new body. This POKéMON’s shell is extremely heavy, making its movements sluggish.
Covering SHELGON’s body are outgrowths much like bones. The shell is very hard and bounces off enemy attacks. When awaiting evolution, this POKéMON hides away in a cavern.
It hardly eats while it awaits evolution. It becomes hardier by enduring hunger. Its shell peels off the instant it begins to evolve.
Its armored body makes all attacks bounce off. The armor is too tough, however, making it heavy and somewhat sluggish.
Within its rugged shell, its cells have begun changing. The shell peels off the instant it evolves.
— Pokédex entries (via PokeAPI)