In the mid-stage evolution, Graveler gains an additional set of arms in the games when it evolves from Geodude, but evolving Graveler to Golem causes it to somehow lose the extra set of limbs ...

The easiest way to initially obtain a Graveler is to catch the Pokémon as a Geodude within Mt. Moon, and you can do this very early on in their game. Geodude evolves into Graveler at level 25.