Dood,
Beast - Claws/SR Scrapper (Mutation)
Iron Fist - MA/SR Scrapper
Superman - Invuln/SS Tanker (Tanker is the only thing that makes sense since the amount of damage that Supes can take without breaking a sweat)
Batman - MA/SR Scrapper (with Devs thrown in, of course)
My beef with the MA set is that there are not enough punch manuevers. You have to add Boxing and Flurry to do something with your hands.
Essentially you want the Tanker's SS as Scrapper available primary. Like how Broadsword and Katana had the same names for powers but different actions, I believe that the Scrapper can have the same name as the attacks (Jab, Punch, etc) but I would not call it SS but rather like Street Fighting or some such. Then you could add Kick and Jump Kick to mix up your attacks between hands and feet.
