Ace appears as the exact opposite of Experiment 627 and Leroy, as he will do virtually any good deed for the sake of being good, due to the glitch in his program. He is also a slight show-off, striking heroic poses for fans after saving the day, and his heroic actions have caused him to become a local do-gooder.
Ace physically resembles a cross between a koala and a dragon, with a superhero-esque posture. He has a muscular body, yellow chest and stomach, white glove-like front paws, a blue nose, pointed ears, and small yellow-tipped antennae. He has a wide mouth with sharp teeth, although he is often shown grinning to form a heroic smile.
Experiment 262 was the 262nd genetic experiment created by Jumba with Hämsterviel's funding. He was designed to be a pure evil experiment, but instead turned out to be pure good, much to Jumba's embarrassment. According to Reuben, Jumba kept 262 locked in the basement when friends came over. 262 and the other first 624 experiments were deactivated and smuggled to Earth by Jumba during his mission to capture Experiment 626.
All of the experiment pods were released and scattered across the island of Kauai, with 262's pod landing in a bush by a house.
Prior to the events of 262, Jumba heard from the head of Evil Genius Organization (EGO). He threatened to revoke Jumba's membership due to believing the latter had reformed and that some of his experiments were not so evil. However, Lilo and Stitch convinced Mortlegax to come visit Earth so they could prove to him that Jumba was still worthy of membership.
When the head of E.G.O. arrived at the Pelekai residence, Lilo and Stitch tried to trick Mortlegax into thinking that Jumba was still evil by showcasing several of his evil experiments on the Internet.
Sometime later, when a fire started in a neighbor's house, a fireman, while trying to put out the fire, accidentally drenched the nearby bush with water from his fire hose, activating 262.
Gantu had been informed about 262, but since the experiment had no evil uses, he didn't bother capturing it.
When 262 heard that the family's pet kitten was trapped inside the burning house, he heroically rushed in and rescued the feline from the fire by jumping out a window with the kitten, using a bedsheet as a parachute. 262, named Ace, then put out the fire using the fireman's hose, and found his one true place as a local do-gooder.
Meanwhile, Lilo and Stitch's facade was successful until the head of E.G.O. saw a screen of Ace rescuing the very same kitten. As a result, Mortlegax revoked Jumba's membership and promptly left. Regardless, Lilo, Nani, Stitch, Jumba and Pleakley all started their own club, with Ace being their newest member.
Later, the first 624 experiments, including Ace, were rounded up by Leroy and taken to a stadium to be destroyed. However, Lilo, Stitch, Jumba, Pleakley, Reuben and Gantu arrived before the experiments could be destroyed.
Ace participated in the following battle between the experiment and the Leroy clones.
The Leroys soon gained the upper hand in the battle, but were defeated when Lilo, Stitch, Reuben and several other experiments performed the song "Aloha ʻOe", which caused the Leroy army to shut down due to the original Leroy's fail-safe.
Ace made an appearance in a bonus episode of the Stitch! anime where he takes Stitch under his wing as a hero. It is revealed that Ace can now not only speak English and fly, but has also become a worldwide superhero. He helped re-energize Stitch after he was almost erased from existence, due to a time-traveling incident in which his creation was tampered with. He later appeared as one of the experiments who helped Stitch fight Dark End.
- Ace is one of the rare experiments that was not evil before he was found by Lilo and Stitch.
- Intriguingly, Ace's number is the opposite of Stitch's, and while Stitch was originally pure evil, Ace was always pure good.
- Ace's pod color is yellow.
- Ace is described by the experiment computer screen as, "Experiment 262. Primary function: Error. Experiment classification failure. 262 has no known evil uses."
- Ace is one of the few experiments to not appear in the group photo at the end of Leroy & Stitch.