Stage Select:
I love when Nintendo throws in little cameos between its own game series. Mario, of course, made a ton of appearances in early NES games. He did some prosaic things like golfing and reffing for tennis and Punch-Out!! but he also piloted the paddle in Alleyway for the Game Boy and you can unlock a Mario statue in the SNES version of Sim City.
I'm playing Monster Hunter Generations Ultimate with some friends and the cat helper of one of my friends has armor that looks just like classic Mega Man, which is pretty cool.
Cage Match:
I think Syphon Filter wins by forfeit because Driver 2 can't get out of parking garage. (Maybe that was Driver 1 that had that ridiculous tutorial but that's what I associate that franchise with.)