Slushy

Slushy, A.K.A. Experiment 523, is an illegal genetic experiment created by Jumba Jookiba. He is designed to make ice and snow, but can also produce snowstorms. His one true place is making Shave Ice with Dupe. He is voiced by Frank Welker.

Personality
Slushy is single-minded. He is a very happy experiment and likes to play with his "cousins" by starting snowball fights. He also messes with his friends sometimes by making the ground slippery or freezing something they need (though he has done it less since Lilo turned him good). He is shown to be aggressive and appears to hold a grudge against Splodyhead, but they resolved it in "Spike". He does like some of the simple things and misses them since he can no longer do them. He also cannot wait to find one of his ohana members so he can play with them again.

Even though most experiments prefer to walk on all fours, 523 likes to walk on his hind legs, but he will walk on all fours to walk faster, or when he's scared.

Lilo & Stitch: The Series
Experiment 523 was the 523rd genetic experiment created by Jumba with Hämsterviel's funding. He was designed to make ice and snow, but could use these powers to convert areas into frozen tundras. 523 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 523's pod landing atop a vending machine.

When Stitch shook the vending machine while trying to get a soda, 523's pod fell out and rolled into a nearby drain, the sewage water activating the experiment. 523 then made his way to a helicopter base, where he stowed away aboard a helicopter and covered the entire island in snow.

Stitch somehow vandalized the soda machine after it malfunctioned before he and Lilo noticed the snowy weather in Kokaua Town, and went home to consult Jumba, who revealed 523 on his computer.

Lilo and Stitch later battled 523 until Gantu eventually arrived, blasted 523 into a net, and captured him in a containment orb. However, Lilo and Stitch were able to get 523 back from Gantu after a brief struggle, and then took 523, whom Lilo named Slushy, back to their house. There, Lilo convinced Slushy to cover her house in more snow so that she and Stitch could have some winter fun.

Although Stitch initially rejected the snow, as it was a form of water, he later joined in the fun and went ice skating and sledding with Lilo. However, while they were busy playing in the snow, Gantu arrived and recaptured Slushy. The former then forced the experiment to cover the island in a massive blizzard and create an ice palace for Gantu.

Sometime later, Lilo and Stitch traveled to the ice palace to defeat Slushy, and made two snow replicas of themselves as bait, which Gantu blasted, thinking it was them. However, Slushy spotted Lilo and Stitch inside and managed to trap them under some huge icicles. Fortunately, Jumba and Pleakley arrived with Splodyhead, who took on Slushy.

A long, drawn-out battle ensued between Slushy and Splodyhead, which ended when the former froze the latter into a block of ice. Splodyhead was eventually freed, and blasted a ball of fire into the sky to clear Slushy's snowstorms.

After Slushy was defeated and recaptured, Lilo and Stitch found him a one true place making Shave Ice.

Slushy reappeared in "Elastico" as one of the audience for Lilo's hula dance.

In "Angel", Slushy was one of the experiments whom Angel reverted to evil using her song, causing the former to go on a rampage by freezing the town. Later, Slushy and the other depraved experiments attacked Stitch aboard a ship, but Angel turned them back to good before they could finish Stitch off. Working together, the experiments were then able to successfully escape the ship.

In "Spike", Slushy was one of the experiments in Pleakley's E.A.R.W.A.X. group. When Slushy created and threw a snowball at Pleakley with boredom, it instead accidentally hit Splodyhead, and a battle ensued between the two experiments, which ended when Pleakley convinced Slushy and Splodyhead to attempt the hugging therapy on each other.

In "Remmy", Slushy was one of the experiments in Lilo's dream.

Slushy and Splodyhead were seen on a computer screen in "Ace", posing as evil creations of Jumba's as part of a hoax to fool the head of E.G.O.

In "Snafu", Slushy and Dupe were seen using their combined powers to sell multiple Shave Ice cones. Gantu then attempted to revert them both to evil by playing a recording of Angel's song, but due to interference from Experiment 120, Gantu's karaoke tape was played instead, much to Slushy and Dupe's humor.

Leroy & Stitch
In the film's opening, Slushy can be seen with Poki as the former sells Shave Ice.

Later, the first 624 experiments, including Slushy, 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.

Slushy participated in the following battle between the experiments and the Leroy clones by freezing oncoming waves of Leroys with his ice breath.

However, 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 `Oe," which caused the Leroy army to shut down due to the original Leroy's fail-safe.

Stitch! anime
Slushy made an appearance in the Stitch! anime along with Pix, Boomer, Blowhard, Kixx, and Slugger when Yuna and Stitch visited Tokyo Disneyland. He makes a second appearance along with Sinker. Hämsterviel uses both of them to attack a cruise ship that he had lured Stitch onto.

Trivia

 * Slushy's pod color is blue.
 * Slushy is described by the experiment computer screen as, "Experiment 523 Primary function: Freeze inducer."