Dexter, a boy-genius with a secret laboratory, constantly battles his sister Dee Dee, who always gains access despite his best efforts to keep her out, as well as his arch-rival and neighbor, Mandark.
Episode 1
In "Deedeemensional", Dee Dee time-travels to save Dexter from a monster. In "Magmanamus", Monkey goes up against a lava being that dislikes human-caused noise. In "Maternal Combat", when his mother falls, Dexter creates a robot mom to substitute for her.
Episode 2
Monkey must defend the city from a giant underground lava monster, Magmanamus, who cannot sleep because of the noise created by its residents.
Episode 3
When his mother falls ill, Dexter creates a robot to do her chores. Dee Dee gets hold of its remote control and wreaks havoc, forcing Dexter to create a second robot to counter Dee Dee's.
Episode 4
Dexter is forced to play dodgeball by his P. E. teacher. Constantly failing, Dexter builds a robotic exoskeleton to defend himself.
Episode 5
Intergalactic wrestling champion Rasslor challenges Earth's superheroes, including Monkey, with the planet's fate at stake.
Episode 6
In need of an assistant to operate his latest invention, Dexter performs a brain transplant on Dee Dee to make her smart enough to fulfill the role. With her new brain, Dee Dee proves to be more intelligent than Dexter.
Episode 7
Mandark Astronomanov, a new student at Dexter's school, seems to be superior to Dexter academically. Mandark forces Dexter to shut down his lab so that Mandark's lab can gain more power. However, with the help of Dee Dee, Dexter manages to destroy Mandark's lab.
Episode 8
Monkey encounters Simion, an intelligent anthropomorphic chimpanzee who seeks vengeance on humans for turning him into his current state.
Episode 9
Banned from watching a late-night movie due to his young age, Dexter uses his technology to artificially grow into adulthood, but Dee Dee tampers with his machine, causing Dexter to turn into an old man.
Episode 10
Dee Dee and her friends, Lee Lee and Mee Mee, enter Dexter's lab and wreak havoc. Dexter clones himself to stop them, but the girls too make clones of themselves.
Episode 11
Monkey's birthday party is interrupted by Barbequor an intergalactic villain who plans to eat the planets, and his sidekick, the Silver Spooner.
Episode 12
Rerun of "Dexter's Laboratory", the first "What a Cartoon!" pilot.
Episode 13
To clone a dinosaur with an incomplete DNA sequence, Dexter uses his dog's genetic code to fill in the gaps.
Episode 14
While on a date with Agent Honeydew, Monkey gets hypnotized by the music of the Organ Grindor who commands him to rob Fort Knox.
Episode 15
Due to overworking his brain, Dexter's mind shuts down, making him act idiotic.
Episode 16
After Dee Dee steals his critical invention, Dexter ventures into her room to find it.
Episode 17
Monkey encounters an alien hunter named Huntor and must fight him to save Agent Honeydew and Commander Chief.
Episode 18
Rerun of the second "What a Cartoon!" pilot.
Episode 19
Dexter and Dee Dee enter tryouts to become Major Glory's sidekick. When Dee Dee wins, Dexter realizes that fancy costumes are not the only criterion to become a superhero.
Episode 20
With only one television in their apartment, Major Glory, Krunk, and Valhallen disagree on what to watch: Major Glory's televised capture of the Disgruntled Postman, TV Puppet Pals, or the monster truck pull.
Episode 21
Dexter and Dee Dee's father buys a video game for them to play, but the game sucks Dexter inside when he plugs in the cartridge, and it is up to Dee Dee to bring him out.
Episode 22
Dexter has a crush on his teenage babysitter Lisa. When he finds out that she has a boyfriend, he sabotages their relationship and accelerates his age by ten years in an attempt to win her heart.
Episode 23
Valhallen loses his magic ax and starts turning into a nerd, forcing Major Glory and Krunk to enter his room to find it.
Episode 24
When Dexter's nightmares become frequent and problematic, he invents a machine that allows him to have nice dreams, as long as Dee Dee can operate it properly while she is awake.
Episode 25
Suspicious that Dee Dee has not entered his lab even once on a particular day, Dexter shrinks himself and enters her room to spy on her. He soon becomes an unwilling character in Dee Dee's doll story, but he believes the story to be real.
Episode 26
While fighting Comrade Red and his gang, Krunk falls in love with his equivalent in their gang, She-Thing.
Episode 27
Dexter's new device allows him to study for the next day's French test while sleeping. It malfunctions, causing a single phrase -omelette du fromage- to repeat throughout the night, causing Dexter to wake up the next morning speaking nothing else except "omelette du fromage".
Episode 28
Dee Dee teaches Dexter how to live life her way instead of being lonely and purely focused on science.
Episode 29
Major Glory forces Krunk and Valhallen to tidy up their apartment for his Uncle Sam, who is coming over for a visit.
Episode 30
To learn more about girls, Dexter camouflages himself and enters Dee Dee's room, where she is having a sleepover with her friends Lee Lee and Mee Mee. He gets caught by the girls, who force him to take part in their activities.
Episode 31
To prevent himself from being taken away by aliens for experimentation, Dexter tricks Dee Dee into going instead, but he regrets his decision after realizing how much he cares for her.
Episode 32
To fix their apartment's plumbing, Krunk and Valhallen go to the basement, where they meet Ratman, a diminutive vigilante raised by rats (a parody of Batman).
Episode 33
Dexter's lab is threatened with repossession unless he can repay his debt to NASA. When Dee Dee wins the same amount in a lottery, he decides to steal her money out of desperation.
Episode 34
Major Glory, Krunk, and Valhallen try to rid their apartment of a bee.
Episode 35
Following the destruction of his lab by Dexter and Dee Dee (in the episode Dexter's Rival), Mandark turns to magic to beat Dexter at the science fair.
Episode 36
Dee Dee inflates Dexter's hydro-plasmatic suit and constantly floats in the air, prompting Dexter to bring her down.
Episode 37
After fellow Justice Friend White Tiger helps Valhallen stop a super-villain, the latter invites him to spend the night in his apartment, forgetting that Major Glory is allergic to cats.
Episode 38
Not interested in hearing Dee Dee's long-winded story, Dexter gives her a silencing formula to keep her quiet, but it instead turns her into a giant monster still bent on telling her story. When he realizes that nothing can make her quiet, he becomes a giant monster himself.
