Captain Falcon, obviously.
I suck at brawl, but I don't care, I gain massive amounts of satisfaction from yelling "FALCON PAWNCH!!!" and then punching people while my fist is on fire. Seriously, this guy would give Doomguy a run for his money as far as badassery goes. Wait... has Captain Falcon ever decided to stay in hell alone for all eternity to prevent demons from ever rising to earth again, his only reward being the safety of mankind? Okay, maybe he wouldn't give Doomguy a run for his money, but still another man in the Hall of Badass.
I'm not very good at SSB anyways. Mortal Kombat is my fighting game. At first I just thought that the game was just way too easy on people, but then I played against other people, human beings... let's just say that I learned how badass Scorpion truly is. This isn't just MK9, this is pretty much all of them.