Reaching the Last Battle
The final sequence features three stages, similar to the previous level featuring the boss Fluffy. Move to either side of the huge robot and neutralize his flamethrowers by freezing them. Once they become frozen, quickly run up and bite them off. Do this until you have eliminated all of the flamethrowers.
Fight the Boss
Run up close to the head of the robot and smash the grates located on its side. When they will open up, go inside of the machine. The enemies will now come in waves. The enemies do not stop, and you must avoid them by moving out of their way. Use the Zappyrang or Flamerang to hit all of the power cables to move onto the next stage. This might take some practice because you will have to shoot and avoid enemies at the same time. When you have destroyed all of the cables, "Total #" will appear on the screen.
Finish off the Boss
Use the Doomerang on the visible gaping hole to release it. Guide the Doomerang through the pipe system until you reach the other end and are presented with an animated cut scene.
"Doomerang" Tips
Keep the "Doomerang" centered and move it only to avoid the oncoming pipes. It will take a few minutes to get through this task. Once you make it through the pipe system, the boss will be finished, and you will get to see the last sequence, along with the rolling credits.