Instructions
Spray paint thinner on the floor in front of the first wave of enemies. Do not spray the enemies directly, or it will take longer to kill them. When you spray the floor, holes open up, and the enemies drop to their death instantly. This trick works on all the enemies in the Coliseum battle area.
Back away from the next group of enemies, leading them toward your existing hole. The enemies will not walk right into the same hole, but you can preserve more of the floor for Mickey to walk on if you make your new hole close to the old one.
Spray more paint thinner on the ground around these enemies. They will drop through the floor and die.
Evade the final group of enemies and back away toward your holes, being careful not to fall in as you lead the enemies.
Spray the ground one last time. When the third group dies, Pete opens up a door that leads through the Coliseum to the Clock Tower. There is also a treasure chest near the door. Be careful to avoid your holes as you walk through the door. If you clumped the holes close together, there should be plenty of floor space for Mickey to safely walk on without having to jump across any large gaps.