Use these cheats to unlock the following options:
Boss Attack Mode: complete either Hero or Dark story modes 1 time
3D green hill Stage: get all 180 emblems to make the stage appear on the world map
Actual Last Stage: complete Hero and Dark story modes, go to story mode and find there a 'Last Stage' option
Hyper Shadow and Super Sonic: complete the Last Stage
Kart Game: finish route 101 with Tails