I still think an Excitebike racer would make for a fun retro character. The game is really well known, and there isn't anyone in Smash Bros. who is permanently attached to a vehicle. He'd certainly be unique.
Standard attacks - bike rams, wheelies, turns, etc.
Air attacks - motocross tricks
Standard (or down) special move - turbo boost
Up special move - ramp jump
Final Smash - Excitebike (ramps and hills appear on the stage as AI-controlled bikers ride around wreaking havoc)

Standard attacks - bike rams, wheelies, turns, etc.
Air attacks - motocross tricks
Standard (or down) special move - turbo boost
Up special move - ramp jump
Final Smash - Excitebike (ramps and hills appear on the stage as AI-controlled bikers ride around wreaking havoc)