Welcome to the FX codes
Blue codes are old, they can be found everywhere or in a few places.
Red codes I've found in mags and sites but I can't get them to work. (they are probably fake)
Green codes- I don't have this game so I can't test it.
Orange codes are discovered by me, you might find them elsewhere but they were here first.
Select a system
Sonic 2
Level Select - Hold Up+Left+1+2 on Controller 2 then turn system on then press 2 twice at the title screen