Graveill is a zombified version of the Pokemon Marill. It is one of many zombie Pokemon to appear in the ROM hack, but it is notable for being one of only two species to be obtainable in the wild, the other being Moulder. It evolves into Azombarill at Level 18.
Graveill's body is essentially the same as Marill's but with a few differenes. Its color is now red instead of blue, and its eyes are just the black, empty sockets with blood coming from them.