Larvitar, the Rock Skin Pokémon. Larvitar generally hatch deep within the earth and take a long time before coming to the surface.
– Ash’s Pokedex
Larvitar is quite rare in the wild. It also evolves at a pretty high level, 30, probably because its final evolution Tyranitar is considered a pseudo-legendary Pokemon.
In the anime, Ash had a Larvitar that hatched from an egg. That Larvitar was emotionally scarred, and would not open to people or other Pokemon. But despite its sprite looking grumpy all the time, the Larvitar in the anime did eventually smile, which looks sort of strange I think.
Stat-wise, its stats are mostly even, with Attack being the highest