Puyo Pop Codes -

Carbunkle:
Defeat Carbunkle and successfully complete the Extra Course level to unlock him in Double Puyo Pop.

Satan:
Defeat Satan in the G. Dark Prince Castle level to unlock Satan in Double Puyo Pop.

Sound test:
Defeat Kaakun two times in the Trial Labyrinth to get Card 18. Enter the options menu and select "Gallery". Choose option 18 to view character artwork. Press A to cycle through the game's sounds.