Mike comes from an NES title called Star Tropics. He is a retro character from a positively reveiwed game and was even on the drawing board for brawl, but removed since his game was never in Japan. But with the "East .vs. West" theme that a Namco Worker claims that Saukarai has for SSB4, he seems a likely canidate.
A. Yo-yo Swing
<-A-> Yo-yo Flick
A ^ Yo-yo Swing Kick
A v Low Yo-yo Flick
B. Yo-yo Spinner: Mike spins his Yo-yo around himself as a sheild and an attack.
<-B-> Star Yo-yo: Mike uses a star power-up to fire a row of stars out in front of him.
B ^ Grip Yo-yo: Mike uses his Yo-yo to grip the ceiling and swing out in a kick.
B V Yo-yo Rotation: Mike spins with his Yo-yo extended, damaging people that get caught.
Final Smash: (Something Yo-yo related)