Credit: Xero, ViperByte, Robb

Adventure Mode Codes
Infinite Lives800B99F8 0004
Max ScoreD0114FE8 0000
80114FE8 FFFF
Enable The Crack of Doom Level800569B0 0001
Enable Four Score Level800569EC 0001
Enable City Wall Level80056A28 0001
Enable Ant May Level80056A64 0001
Enable Trapped Under Ice Level80056AA0 0001
Enable A Glacier Runs Through It Level80056B18 0001
Enable Iceburg Let Us Level80056B54 0001
Enable Celtic Frost Level80056B90 0001
Enable Motel of Lost Champions Level80056BCC 0001
Enable Huckleberry Friend Level80056C08 0001
Enable Jump in The Fire Level80056C44 0001
Enable A Bridge Over Molten Magma Level80056C80 0001
Enable Schmokenden Level80056CBC 0001
Enable Furnace of Fools Level80056CF8 0001
Enable But It's A Dry Heat Level80056D34 0001
Enable Born of Fire Level80056D70 0001
Enable A Hero's Reckoning Level80056DAC 0001
Enable This Mad Machinery Level80056F50 0001
Enable Curiosity Caught the Wee Level80056F8C 0001
Enable Things Crawl in the Darkness Level80056FC8 0001
Enable Your Back's Against No Wall Level80057004 0001
Enable Her Dead Power, The Queen Pede Level80057040 0001
Have Last Level Completed8005707C 0001
When Paused Press Right To Gain Extra Lives800B96CC 0001
Arcade Mode Codes
P1 Infinite Lives80095DCC 0003
P2 Infinite Lives80095DD0 0002