Arson, Murder, and Jaywalking: When Mojo is turned into a dog after the curse is reversed at the end of the episode, the girls ask the Professor if they can keep him as a pet. The Professor reminds the girls that if they do, they'll need to stop him from causing mayhem, chaos, and chewing the furniture.
Artifact of Doom: The Anubis Dog Head and its 2 corresponding ruby eyes. When combined, they give the wielder the power to turn everyone into dogs.
Baleful Polymorph: Mojo Jojo uses the Anubis Dog Head to turn everyone, including the girls, into dogs.
His Name Is...: The first human-turned-dog and the Mayor try to explain who is responsible for everyone turning into dogs, but their speech turns into barking just before they could say the name.
Killed Mid-Sentence: A non-fatal example; The Mayor, who is already half dog completes his transformation just as he's about to say Mojo's name. Same with the first talking dog the girls run in to, who begs for help before being reduced to barks.
Laser-Guided Karma: Mojo gets a little too cocky and thus is easy prey for Buttercup when she bites him in the butt, causing him to break the Anubis Dog Head; the resulting shockwave restores everyone to normal and leaves him as a mutt. Bonus points for being the effect of an actual laser.
Literal-Minded: As a dog, Professor Utonium can only say "Bow Wow Wow Wow" when reciting Mojo's name. Bubbles misinterprets this as the villain's real name until Blossom realizes what he actually meant to say.
Morphic Resonance: When the citizens turn into dogs, they retain some of their traits when they were human. For example, the girls' fur is the same as their hair colors and they retain their faces, while the Professor's fur is the same white as his coat.
Caught Coming Home Late: Twice: The first time is the traditional "parent catches child" setup, as the girls return after fighting crime and Sedusa catches them. The second time has the roles reverse, as Sedusa returns after a crime spree and the girls catch her.
Didn't Think This Through: Sedusa didn't take any precautions to prevent the Mayor from calling the Powerpuff Girls for help, and instead of making off with her prize she returns to the Girls' house with her stash of jewels. By then, the Girls had already put all the pieces together.
Earn Your Happy Ending: When Professor decides to tell girls to call the police to arrest Sedusa. And Professor tells the girls Sedusa will not deceive him anymore.
Here We Go Again!: Said by the Narrator at the end where another woman shows up and baked a pie for the Professor and the girls when she heard about Sedusa being caught.
Ironic Echo: When the girls return home after fighting crime past their curfew, Ima/Sedusa stops them in their tracks by saying, "And just where have you three been? Well?" When Sedusa returns home after stealing the Mayor's jewels, the girls stop her in her tracks by saying the exact same thing.
Jerkass Has a Point: Subverted. "Ima" seems somewhat justified in making the girls clean up the huge mess they caused before allowing them to fight crime, but than after they do so she messes up the living room again and makes them clean without their powers.
Meaningful Name / Ironic Name: Sedusas alias name is Ima Goodlady (Im a good lady), which she appears to be indeed at first. Of course, she is anything but, making it the later trope.
Papa Wolf: The Professor becomes this when he finally sees who his girlfriend actually is, and restrains her until the police arrive.
Wicked Stepmother: Ima/Sedusa is this to the girls....or rather, might have, if the Professor married her.
Why Did It Have To Be The Dark?: In this episode, Bubbles is revealed to be afraid of the dark, which means the Professor has to leave the hall light on and crack the bedroom door open just a tiny bit so that Bubbles can go to sleep.
Wounded Gazelle Gambit: Sedusa pulls one on the Professor twice to get him to ground the girls. The latter one fails miserably due to her identity being exposed and she ends up arrested.
You Are Grounded: Sedusa, as Ima Goodlady, makes sure the girls get grounded so they wont interfere with her evil plans. She even says it word for word.