Hulk, The

Invulnerability:
Select the "Code Input" selection at the options screen, then 
enter GMMSKIN as a code to unlock this option at the cheats menu. 
The Hulk and Bruce Banner will be invincible.
 
Regenerator:
Select the "Code Input" selection at the options screen, then 
enter FLSHWND as a code to unlock this option at the cheats menu. 
The Hulk will regenerate faster. 
 
Full Rage Meter:
Select the "Code Input" selection at the options screen, then 
enter ANGMNGT as a code to unlock this option at the cheats menu. 
The Rage meter always remains full.
 
Unlimited Continues:
Select the "Code Input" selection at the options screen, then 
enter GRNCHTR as a code to unlock this option at the cheats menu. 
 
Double Hulk's HP:
Select the "Code Input" selection at the options screen, then 
enter HLTHDSE as a code to unlock this option at the cheats menu. 
 
Double All Enemies HP:
Select the "Code Input" selection at the options screen, then 
enter BRNGITN as a code to unlock this option at the cheats menu. 
 
Half All Enemies HP:
Select the "Code Input" selection at the options screen, then 
enter MMMYHLP as a code to unlock this option at the cheats menu. 
 
Wicked Punch:
Select the "Code Input" selection at the options screen, then 
enter FSTOFRY as a code to unlock this option at the cheats menu. 
The Hulk will have one hit kills. 
 
Puzzle Solved:
Select the "Code Input" selection at the options screen, then 
enter BRCESTN as a code to unlock this option at the cheats menu. 
Puzzles will immediately be solved. 
 
Reset High Score:
Select the "Code Input" selection at the options screen, then 
enter NMBTHIH as a code to unlock this option at the cheats menu. 

Unlock All Levels:
Select the "Code Input" selection at the options screen, then 
enter TRUBLVR as a code to unlock this option at the cheats menu. 

Note: This will also unlock all of the challenge modes.

Hulk Transformed movie art:
Find a terminal during game play, then enter SANFRAN as a code. 

Hulk vs. Hulk Dogs movie art:
Find a terminal during game play, then enter PITBULL as a code. 

Desert Battle movie art:
Find a terminal during game play, then enter FIFTEEN as a code. 

Hulk Movie F/X movie art:
Find a terminal during game play, then enter NANOMED as a code. 

Play as Gray Hulk:
Find a terminal during game play, then enter JANITOR as a code.