Coop and the rest of the kids need Kat's help to escape Kat Planet. Will he give it?
When Kat is fired for incompetence the Robo-Kat-Kops that are sent to take him home also capture Coop, Dennis, Fiona, Millie, Lorne, and Harley and take them to the Kat Planet.
Kat controls the mind of Agent Napolitan, but his plan backfires when some squirrels attack him.
Kat thinks the haunted LeBoot Mansion will be the perfect place for an inter-space teleporter.
Kat shrinks Coop and Dennis down to size and tries to squash them like bugs, which makes it hard for Coop to do something big for Dad for Father's Day.
Kat and Old Lady Munson show up at school where they work together to make Coop's life miserable.
Coop and Fiona have to settle their argument before they can work together to stop Kat in his evil tracks.
Buck Diamond, Animal Protection Officer declares Coop "Bootsville's Most Wanted".
Kat makes himself a high-powered good luck charm, which means bad luck for Coop.
Coop takes on the teen aged bully who pedals the Curly Swirl Ice Cream cart, and forgets to pay attention to Kat's latest evil plans.
Kat turns Coop into a cave man, hoping his lowered I.Q. will make him easier to outsmart. Now Dennis must change Coop back to human.
Kat soups up Coop's new soccer shoes to allow the wearer to run faster and jump higher, and Coop wears the shoes in the championship game.
It's Hot Dog Day, and Coop has the honor of being named Keeper of the Weiner Water. But Kat wants to ruin the most special day of the year.
Coop and Dennis battle Kat's army of living hairballs.
Kat builds a device that brings an assortment of movie monsters to life.
Kat's memory eraser leads to Coop forgetting Kat is an evil alien, but Dad accidentally gets Coop's lost memories and suddenly knows the terrible truth.
Coop discovers buried treasure under Old Lady Munson's house.
Coop and Kat fight over the animal's new lightning box generator and end up swapping brains.
Coop goes on a train to buy something from a man named Old Herman, Unfortunately it turns out to be the evil alien hamster, Mr. Cheeks!
Dad orders Coop to spend more quality time with his little sister; Kat builds a telepathy helmet.
Coop's birthday is here, and everyone is coming to his party, and Phoebe is trying to get rid of Fiona so she can have Coop to herself. Meanwhile, Kat is trying to enjoy a virtual picnic in a secluded spot with his girlfriend, but the kids and Coop keep crashing Coop's birthday.
The evil alien hamster Mr. Cheeks comes back to get revenge on his nemesis, Kat.
Old Lady Munson tells Millie creative stories about her adventures in the past.
Old Lady Munson's garden gnomes come to life and mistake Coop as their leader.
Coop searches for the last available bag of the feline's favorite food after the factory that makes it closes down so he can taunt Kat.
Coop's grandparents visit, so Dad buys them rocking chairs. However, it turns out they are adventure junkies who accept that Kat is an alien.
Kat makes himself invisible and causes trouble for Coop on the night he invites Fiona to dinner and when Dad invites Coop's teacher over for dinner.
Dennis is accidentally knocked into a portal around the world.
Kat becomes obsessed with making the biggest yarn ball ever made, and starts rustling sheep to gather their wool.
Kat is left at a kennel while the Burtonburgers go on vacation.
Dad accidentally swaps an assortment of Kat's weapons to the unwitting residents of Bootsville.
The Kat Kommander's rebellious son runs away to Earth, where he becomes a handful for Kat, and a danger to the human race.
Kat's malfunctioning spybot thinks Coop is its new master, and wants to protect him from Kat.
Growler swallows a Kat device which makes him grow to the size of a T-Rex.
Coop breaks every window in Dennis' house, and is forced to work off his debt by working in Henry's store.
Coop becomes Dennis’ wing-man for a change, as they go in search of the 'sewer-croc-baby'.
Coop tries to undo the Kat invasion, which he brought about by fooling with Kat’s time machine.
Coop uses Kat’s time machine to go back to the past and stop Millie from bringing Kat home, but ends up altering the future for the worse.
Coop and Dennis compete with one another to reduce their carbon footprints.
Kat’s devious magnifier satellite is causing a dangerous heat wave in Bootsville.
Due to an ‘over-loading’ problem on the Kat Nebula, Kat plots to turn Bootsville Beach into a giant litter box.
After taking the fall for one too many of Kat's destructive escapades, Coop decides to let Kat have free rein to cause whatever destruction he wants.
Coop, Millie, and Dad are taken away to a top secret base to be interrogated, after a UFO investigator suspects they are aliens.
Coop and Dennis climb inside Kat's scratching post and discover Kat's alien technology has created an infinity within.
Kat builds a Rat-ray gun, which he plans on using to turn Coop into a rat, but Dad gets zapped instead, so Coop hopes he can change Dad back... If he can catch him first!
Coop tries to stop the destruction of Massive Mart.
When Kat uses his growth ray to bury Bootsville in a catnip jungle, Coop is blamed by the irate Bootsville Gardening Club.
Millie brings home the class hamster, unaware that Mr. Kat hates hamsters.
With Coop out of town, Kat wants to turn water into milk and Dennis comes to the rescue.
Kat's swarm of flea-sized mind control robots hop into the ears of the people of Bootsville and soon they all destroy Coop.
When Millie tickles Mr. Kat's 'tickle spot' he goes into a blissful state that renders him useless as an alien agent and when Kat's empire find out about him they send a robot to destroy Millie.
Coop falls for Old Lady Munson’s niece Fiona, and Kat does everything he can to make Coop look bad.
