Scrafty is most likely based off of some sort of reptile. One piece evidence being that Scrafty's pokedex entry for Black states that it's capable of shooting acid from it's mouth, similar to certain types of Cobras. Another piece of evidence is Scrafty's uncommon ability, Shed Skin. Many Lizards and Snakes are known for sheding their skin, so Scrafty fits right in. My final piece of evidence is the fact that Scraty can learn a few Dragon moves, such as Dragon Pulse, Claw, Dance, Tail, Dual Chop, and Outrage. So Scrafty could possibly a Lizard, or probably a small Dragon. And while Scrafty does share some traits with humans, such as the Mohawk of Hood, so do a lot of Pokemon, such as Mewtwo, or a lot of other fighting types.