http://multiverseworks.com/smashicon.php
All of the confirmed Brawl logos so far, they have all been ranked by number. Interestingly, numbers 13 and 19 are missing.
If you observe it well, you can see there is a noticeable pattern, it lists all the logos of the original SSB characters first, then the new characters in SSBM and then the new characters in SSBB.
So Mr. Game & Watch is undeniably 13, his return is a genuine guarantee. Now the big question is, whats logo number 19?
I wish there were further clues to rely on.