Dr. Muto

Invincibility:
Enter NECROSCI as a code. 

Note: This has no effect when you fall from high places. 

Never take damage:
Enter CHEATERBOY as a code. 

All Gadgets:
Enter TINKERTOY as a code. 

Secret Morphs:
Enter LOGGLOGG as a code. 

All Morphs:
Enter EUREKA as a code. 

Go anywhere:
Enter BEAMMEUP as a code. 

View FMV sequences:
Enter HOTTICKET as a code. 

Super ending:
Enter BUZZOFF as a code.