Slick is generally very friendly and polite, tipping his hat every time he greets somebody, but is rather obsessive about selling stuff. He won't stop selling until there is nothing left to sell, even selling himself to Mertle through a live auction. He is also very kind-hearted and courteous, and strongly supports his one true place working for charity.
Despite being incredibly friendly, he can also be amazingly fierce. This was shown during the final battle from Leroy & Stitch. His initial facial expression after Stitch's pep talk was fearsome, and at one point during the battle, he had a Leroy clone running from him. So, he can easily turn from a friendly salesman to a terrifying fighter, while still keeping his good intentions.
Experiment 020 was the 20th genetic experiment created by Jumba with Hämsterviel's funding. He was designed to sell anything, including other experiments, to unsuspecting victims. 020 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.
At an unknown point after this, Experiment 020 was activated.
Lilo and Stitch were both having trouble selling chocolate bars for a hula halau, and passed 020 sitting on a park bench reading a newspaper. When 020 heard Lilo and Stitch's problem, he introduced himself to them and presented his card, which revealed his number and primary function.
When Lilo and Stitch discovered 020's powers, the former named him Slick and took him in to try to sell some candy bars. Using his sales pitch, Slick managed to convince every person whom Lilo came across into buying one of her chocolate bars.
However, Slick soon began selling everything that the Pelekais owned. Since they were unable to capture Slick (as he had sold all their containment orbs as well), Lilo left Pleakley in charge of Slick while she and Stitch set out to reclaim all of their personal belongings before it was too late.
While they were doing this, Mertle, who somehow found out about Slick, showed up at the Pelekais' house looking for the master salesman. Annoyed, Pleakley tried to get Mertle to leave, but Slick, who refused to turn down a customer, allowed her to come in. When both rivals demanded custody of Slick, the latter held an indoor auction and set the opening bid at one dollar. The auction ended with Slick selling himself to Mertle for three dollars.
After Lilo and Stitch managed to retrieve all of their household possessions, they returned home to discover that Slick was gone. Pleakley explained what happened, prompting Lilo and Stitch to get Slick back.
Meanwhile, Mertle used Slick to solicit candy bars and win the fundraiser until Lilo and Stitch stole him, but Mertle managed to steal him back. Later, when Lilo and Stitch went over to Mertle's house to reclaim Slick, Mertle revealed that she sold him to Experiment 625, much to their horror.
At Gantu's ship, Slick chatted amicably with Reuben and later sold the spacecraft to an old man, who had somehow gained entry. However, Slick was eventually captured by a sick Gantu, who had been repeatedly persuaded by Hämsterviel to do so.
Fortunately, Lilo and Stitch arrived and managed to rescue Slick, but Gantu was able to track him down and recapture him. However, Gantu ended up trading Slick for Lilo's last chocolate bar, claiming it would cure his cold.
Shortly after, Slick found his one true place in raising money for charity.
In "Remmy", Slick was one of the experiments in Lilo's dream.
Slick was one of the experiments that was gliding on the screen, but he is 597 instead of 020.
The first 624 experiments, including Slick, 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.
Slick participated in the following battle between the experiments and the Leroy clones, having frightened at least one Leroy clone.
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.
- Slick's pod color is red.
- Slick is described by the experiment computer screen as, "Experiment 020 Primary function: Salesman."