Super Pierrot or Pierrot is the boss of Toy Island.
Compared to the previous boss, the Clown is much easier to defeat. He bounces around the room at 45 degree angles, and releases up to four smaller clowns to help him attack you. But none of the clowns move with any purpose, and they're very predictable. Prioritize your safety by making sure you don't stand where any of the clowns are going to move to. Then create as many rainbows all around as you can in order to attack the clowns, and crush the boss with as many rainbows as possible.