At the character selection screen enter:

igotcatslife - start playing with 9 lives
masterofthisgame - see photo creator
givemesomerings - start playing with 50 rings
makeithard - turn off the ring levels
warptolava - go to the level of Lava Reef
warptoangel - go to the level of Angel Island
warptomushroom - go to the level of Mushroom Hill
warptomarble - go to the level of Marble Garden
warptoice - go to the level of Ice Cap
warptohill - go to the level of Hill Top
warptosky - go to the level of last battle
stayaway - disable bad nicknames
savetheplanet - see the last scene