Hell Mode
To unlock Hell mode, beat Story mode on the Hard difficulty.
Unlock Hard Mode
Beat the game on Normal Mode.
Chao hairstyle/NiGHTS Wig/Sonic Wig/Ulala hairstyles
Beat hell mode.
Chao hairstyle
Have Sonic Advance 3 inserted into the GBA slot.
NiGHTS Wig
Start Feel the Magic with either Chu Chu Rocket or Sonic Pinball Party in the GBA Slot.
Sonic Wig Start
Feel the Magic with either Sonic Advance or Soinc Advance 2 in the GBA Slot.
Ulala hairstyle
Have Sonic Battle inserted into the GBA slot.
Ulala hairstyle
Have Space Channel 5: Ulala's Cosmic Attack inserted into the GBA slot.
Girl on Menu Screen Loses Her Top
Simply set the language to Japanese, and the girl mysteriously loses her top.