Enter the following as passwords:

5656    One player battle mode
4622    Get all power-ups

Password  Level  
8566        1      
9634        2      
1637        3      
0320        4      
6524        5      
3260        6      
4783        7      
5472        8 

GameShark Codes

Note: You must have a 2.1 or higher version of the Game Shark to use these
codes in a Game Boy Color system.

Invincible 014082CE
 

Thanks to Revolution readers Impecable Master and JohnBrown!