Plasmoid

 Plasmoid, A.K.A. Experiment 617, is an illegal genetic experiment created by Jumba Jookiba. He is designed to fire plasma blasts from his scorpion-like tail. He was captured by Gantu, but was rescued in "Snafu." His one true place is at First National Hawaiian Bank. Plasmoid is voiced by Frank Welker.

Bio
Experiment 617 was the 617th genetic experiment created by Jumba with Hämsterviel's funding. He was designed to fire balls of plasma from his scorpion-like tail.

617 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.

Lilo & Stitch: The Series
617's pod eventually made its way to a junk shop, where it, along with 544, 609 and 033, was stolen by Gantu, activated, and named Plasmoid in "Dupe."

Plasmoid, Heat, Thresher and Hammerface were then led by Gantu in an attack on the Pelekais' house, where Plasmoid and the other three experiments were able to easily defeat and capture Stitch and his replicas.

The five returned to Gantu's ship for a victory feast, but were interrupted by Lilo, Pleakley and Dupe. Gantu used Dupe to clone Plasmoid into a hundred replicas, but as Plasmoid's power was thus divided between them, they were complete weaklings.

It is presumed that Hämsterviel was somehow able to re-merge the weakling Plasmoids into one.

Plasmoid reappeared in "Snafu," and was freed along with Gantu's other captive experiments by Lilo, Stitch, and several other experiments in a rescue mission.

Leroy & Stitch
The first 624 experiments, including Plasmoid, 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.

Plasmoid participated in the following battle between the experiments and the Leroy clones by firing plasma blasts at Leroys.

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 failsafe.

Stitch! anime
Plasmoid has appeared twice in the Stitch! anime, both times with Splodyhead. In the first appearance, he and Splodyhead fought against Stitch when he was hypnotized by Swirly into fighting for Hämsterviel. In the second appearance, he and Splodyhead were modified by Hamsterviel to attack Stitch. Plasmoid was given a new ability of vacuuming up objects and using them as projectiles.

Trivia

 * Plasmoid is one of the eight known experiments named by someone other than Lilo, the other seven being Yaarp, Gigi, Elastico, Hammerface, Thresher, Heat, and Shrink.
 * Plasmoid's pod color is blue.
 * Plasmoid is described by the experiment computer screen that says "Experiment 617 Primary function: Plasma shooter."