Smash Bros:
It would be awesome to encompase every Fighter, Every Costume, Every Stage, Every Trophies, and Every Event from all 5 games and project M.
Crash Bandicoot:
1,2,3,4,and Twinsanity
Grand Theft Auto 3D
Who hasn't wanted all of the PS2 Era maps in 1 game. Liberty City, Vice City, San Andreas, Bullworth, Carson, and Cottonmouth.
F-Zero
The best tracks from F-zero, F-zero X, F-zero X DD, and F-zero GX all in one game with the GP legend racers would be awesome.