Super boxer:
Select career mode at the title screen and create a new fighter using the name THE_BEAST. A green fighter all attributes set to full will appear.

Skip bouts:
Enable the "Super boxer" code. Fight the next boxer. Wait for the camera to move after The Beast raises his hand. Press Start and quit the bout when neither boxer is in view, and the camera shows the ropes and ring post. A win will be awarded to The Beast. Train to recover the power that was lost. Repeat this process to reach the championship.