When fighting the Painter in the Wizard's Castle, take a look at his brush. Its color can help you anticipate what he will paint:

Light Pink - Unicorn
Orange - Carrot Clock
Teal - Angry Person
Red - Big Monster
Purple - Octopus
Magenta - Clown
Turquoise - Zombie
Light Orange - Cat
White - Elephant
Light Purple - Nose-Snail