Dexter travels to the moon and finds that aliens are planning an invasion on Earth, and he uses his Robo-Dexo 2000 to stop them. It turns out that they only were interested in purchasing sweaters for the winter.
Dexter tries to prove to Dee Dee that Santa Claus is not real and is in fact their father in disguise. He ends up paying for his mistake when he has captured the real Santa Claus.
Dexter finds the exact opposite of his family, a hyperactive boy who is like Dee Dee and has scientist parents who are like Dexter. Sensing to fit in, he switches places with the boy.
The U.S. army invades Dexter’s lab under the mistaken impression that aliens are using it as a base of operations on Earth, and Dexter must convince them that this is actually his lab, and also has to keep this a secret from Dee Dee.
On his birthday, Dexter makes himself invisible so that he can find out whether his parents have bought him the Major Glory action figure he always wanted.
When Dee Dee tries to cut off a piece of her hair, she accidentally cuts off one of her pigtails. Dexter gives her a potion to make her missing hair grow back. However, Dee Dee squirts too much of it in her hair, and Dexter must return Dee Dee’s hair back to normal.
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.
Dee Dee dares Dexter into building her a giant robot similar to his Robo-Dexo 2000. They then team up to try to save an island’s population from being destroyed by an erupting volcano using their giant robots.
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.
After Dee Dee declares that she can beat Dexter in any game, Dexter challenges her to a series of games in his lab, though he prefers to win by cheating.
Mandark gets inside Dexter’s computer system and creates a computer virus, so Dexter must follow him inside and kick him out from cyberspace. However, Dee Dee has other plans in mind.
When Dexter tries to inject himself into an ill Dee Dee to find a cure to the common cold, he accidentally ends up inside his dog, believing that Dee Dee is infected with a dog virus.
Dexter reluctantly takes piano lessons from Professor Williams (Paul Williams), but when the Professor stumbles onto Dexter’s lab, he discovers that Dexter has more musical talent than he thought.
