Save Mojo: When the Powerpuff Girls try to stop Mojo Jojo from doing a crime, an animal activist group comes to his rescue protesting that the Powerpuff Girls can't harm him because he is an endangered animal.
Substitute Creature: When Ms. Keane gets sick, she hires a substitute teacher named Mr. Green to run the class in her absence. Unfortunately, because of his monstorous appearance, the girls assume he is a bad guy and try to save their classmates from him.
Save Mojo provides examples of:
- All Your Base Are Belong to Us: Mojo even attacks the girls own home to steal some of the professors equipment.
- Animal Wrongs Group: the animal activists; they actively prevent the girls from harassing" Mojo Jojo, not caring that Mojo is clearly a villain committing crimes and the girls merely wants to stop him. The girls eventually turn it against Mojo by helping the activists move Mojo into the wild
- Crocodile Tears: Mojo happily pretends to be a helpless animal in order to gain the sympathy, and thus protection, from the activists.
- New-Age Retro Hippie: the animal activists all look like these.
- Paper-Thin Disguise: Mojos disguise at the beginning of the episode. The narrator even calls it pathetic.
- Waving Signs Around: the animal activists.
Substitue Creature provides examples of:
- Dark Is Not Evil: Mr. Green is a prime example of this trope.
- Expressive Accessory: Blossom's bow droops when Mr. Green asks her to give the kids cookies.
- Eyepatch of Power: Mr. Green has one.
- Imagine Spot: The girls repeatedly imagine Mr. Green doing horrible things to Mrs. Keane and their class mates, but none of these fantasies ever come true.
- Heel Realization: the girls realize they were the bad guys here for wrongfully assuming the Mr. Green was a threat.
- Reluctant Monster: Mr. Green looks like a demon, but truly likes children and wants to be a good teacher.
- White Hair, Black Heart: Mr. Green has white hair, but the Black Heart part is eventually averted as the girls learn he is not evil.