Experiment 234, designed to collect private enemy conversations through her tail, is accidentally activated by Lilo. When she gets into trouble after overhearing part of a conversion and thinking that Mertle hates her friends, Mertle, out of anger, willingly helps catch experiments for Hamsterviel.

It's Lilo's birthday, but no one has remembered. So, she decides to give herself her own party. However, during the day, Experiment #303 is activated and wipes Lilo's, Stitch's and Gantu's memory. Lilo and Gantu, who think they are Martha and Lenny go after Stitch, who has returned to his natural destructive programming, and so they think is a criminal.

Experiment #344 - Dupe Lilo and Stitch have managed to capture Experiment #344, who can duplicate anything. This leaves Gantu feeling down, so he goes home to talk to 625 about it. However, 625 gets bored and tells him he doesn't care, causing Gantu to go off in a rage. Meanwhile, Lilo, who has hosted a slumber party but no one turned up, decides to clone herself using #344, but Stitch jumps in the way, creating an extra 3 copies of himself, who all need training. Gantu, in his rage, discovers 4 experiment pods: Heat, Plasmoid, Thrasher and HammerFace. He activates them and plans an attack on Lilo and Stitch. But surely 4 Stitches can beat Gantu.. Right?

Pleakley's mother is badgering him about finding a wife, and has even found a perfect candidate on his home planet, so Lilo comes up with an idea: To tell his mom he is already engaged to a human. But Pleakley's family turn up on Earth, so Pleakley must put on a fake wedding, passing Nani as his bride-to-be. But Experiment #032 has turned up, Fibber, and will beep whenever someone is lying. So, as Pleakley tries to plan his fake wedding, Lilo and Stitch have to prevent Fibber from giving away the game.

The Hula Girls have ditched Mertle for Lilo, and consequently, Lilo neglects Stitch to hang with them at the Kauai Medieval Festival. So, when Experiment #586 is activated, Stitch needs someone to capture it with. And who does he team up with? Mertle. Strangely, Stitch and Mertle are having fun trying to capture the metal eater, but this ends when it storms the Medieval Festival.

Lilo finds the pod for Experiment #509, which is a plant experiment. Lilo wants to activate to find it's true place, but Jumba won't let her and locks it up. However, when she makes a bet with Mertle, she breaks the lock and activates #509 and dubs it Sprout. But things get out of control at the Kauai Town Fair, and Stitch has a showdown with a cowboy.

Lilo is going to perform a Hula Dance, but gets angry when Stitch gets in her way. He runs away and finds Experiment #345, Elastico, who is performing at a local circus. Gantu arrives, though, and steals Elastico. The Ringmaster lets Stitch take Elastico's place. He invites Lilo to visit him, but she refuses. Soon Elastico escapes Gantu and returns to the circus, and Lilo needs Stitch to dance, so has to look for him. But which ohana will Stitch choose?

Experiment #604 - Houdini Stitch and Pleakley are working up a terrible magic act to perform at one of Mertle's parties, so Lilo secretly helps them out by activating Experiment #303, Houdini, which can make things disappear and reappear with a blink of it's eyes. But when Gantu crashes the party, things go wrong, and Stitch is made invisible and Houdini gets away. And just to make things worse, Mertle's aunt, who is a big LA producer, wants to make Stitch a star because of his magic act, but only Lilo, Jumba, Pleakley and Houdini know it is phony.

Experiment #523 - Slushy A giant heatwave has struck Kauai. Lilo is trying to get Stitch to try something to escape the heat, but Stitch just refuses: He's a creature of habit, and won't try new things. As he tries to get a cold sofa, he activates Experiment #509, an ice experiment from the elemental series, who has frosty breath that can transform any town into a frozen one.

Experiment #624 - Angel Experiment #624 has been activated by Gantu, and is used as a secret weapon to try to turn Stitch evil. But because Stitch is more advanced than #624, aka Angel, her evil song doesn't work on either him or 625. Her song does work, however, on the other 623 experiments, so she makes up an army of the experiments on the island. Meanwhile, Stitch tries to get Angel's affections, and Lilo experiences jealousy.

Experiment 062: FRENCHFRY When Nani restricts Lilo's food to healthy food, Lilo finds an experiment pod that is designed to make tasty, irresistible food, but he is secretly fattening them up to eat them. Will they be saved in time?

Lilo & Stitch learn that Mrs. Hasagawa has adopted a lot of cats that are not cats at all but experiments.

Experiment #458 - Finder Experiment #458 can find absolutely anything, so Lilo names him Finder. And when she takes him to show-and-tell, he's a huge hit, upstaging Mertle. Mertle is bitter, so she searches for something to compete with Lilo's show-and-tell. Unfortunately, she is unsuccessful. That is, until she sees Hamsterviel on planet Earth!

Experiment #297 - ShortStuff Stitch is getting really upset about people thinking he's too short, so Pleakley uses Jumba's growing ray to make Stitch bigger. Meanwhile, an experiment is activated and it is soon short circuiting mechanical devices all over the island.

Experiment 355: SWAPPER When Swapper swaps Lilo and Stitch's brains, Lilo thinks it will be impossible to get Victoria, a new girl, to think that she's not weird.

When Dr. Drakken and Hämsterviel team up to kidnap Stitch in order to mass multiply him in order to destroy the world, Kim Possible and Lilo set off to try and save Experiment 626. Jumba, on the other hand, is quite sure that a certain Naked Mole Rat is his experiment 607...

Nosy, (who escaped at from Gantu's ship at the end of Woops,) complains to Lilo about the fact that she just left all the experiments behind and never found their one true place. (Lilo and Stitch never went back and saved them). So, Lilo plans to save them, especially Angel. But when Snafu, a plan ruiner is on the loose, will Lilo be able to save Stitch's cousins?

Experiments #501 and #502 are both activated at the same time, a water sprayer and a lava sprayer. Unfortunately, Lilo and Stitch are having some problems with each other, and soon decide to split apart, with Lilo teaming up with Pleakley, and Stitch teaming up with Jumba. Can the 2 capture the experiments without their partner?

Mrs. Hasagawa is watering her vegetables innocently one morning. However, she activates Experiment #613, Yaarp, which is designed to destroy buildings with it's sonic blasts. Lilo and Stitch are hot on it's trail, when it yarps, and because of Stitch's super hearing, Stitch is temporarily deaf. So, when Jumba says only someone with no ears could be safe from Yaarp, Pleakley is on the stage as an Experiment Hunter. Pleakley catches Yaarp, but Stitch's plan to deter Gantu away from the hunt goes wrong, and he captures Stitch. And now he is offering Lilo a trade: Stitch for Yaarp.

In a trip to the observatory, Lilo and Stitch overhear Cobra telling an astronomer about a huge asteroid heading towards Earth. Lilo and Stitch go around Kauai telling the people to evacuate with them onto their ship. Stitch also warns his cousins. However, only 6 Experiments - Digger, Swirly, Hammerhead, Sparky, Spooky and Kixx - and a surfer from the beach arrive at the ship. So, Stitch comes up with a new idea; Digger will drill a hole to the center of the asteroid, it can be smashed. Things seem to be going to plan, but they soon find out something lives on the asteroid, and their plan comes crashing down.

Experiment #602 - Sinker Lilo is having high hopes for Keoni and his sailboat entry in a regatta, until his boat is sliced in half by Experiment #602. Soon Lilo, Stitch, Jumba and Pleakley are stowaways on a cruise ship. So while Pleakley is fascinated by shuffleboard, and Stitch digs into the buffet, Lilo must find the ship's Captain and warn him about Experiment #602.

Experiment 319: SPIKE Lilo and co. set out to beat Myrtle and her family in the Ohana-Rama.

Experiment 113: SHOE When bills go high Lilo tries to earn money by Mertle's idea: A bed and breakfast. However, experiment 113 is activated and is causing bad luck at Jumba and Pleakley's Bed and not Breakfeast.

Experiment 089: SKIP Lilo's desire to hurry and grow up is immediately satisfied when Skip, experiment 089, arrives and ages her up to a 17-year-old and then a 27-year-old. Lilo soon realizes she wants to be age 7 again because she misses out and ruins the future. She must figure out how to "reset" herself.

Stitch won't listen to Lilo's advice about trying to see the good in people, and will go to any lengths to stop him capturing an experiment pod, including racing to a neighbouring desert island, with Lilo, Jumba and Pleakley in tow. But after the camp of the 'hunting parties' are destroyed, Stitch and Gantu blame each other. Turns out it's an experiment. Who will capture Splodyhead?