(1)Mario vs. Bowser vs (2)Sonic the Hedgehog vs. Dr. Robotnik 2011

Ulti's Analysis
Our first Mario vs Sonic match of any contest in any contest (even those Battle Royale things), and we get... an SFF beating not worth talking about. Lovely.

Mario v Sonic is a weird beast, because Sonic either overperforms or gets crushed with no in between (Mario v Shadow in 2003, Mario World v Sonic 2 in 2004). And no, this doesn't mean Mario v Sonic as an entry this contest would have flopped. I'm convinced Mario/Sonic win this contest, given how bad Link did in the final.