Spats

 Spats, A.K.A. Experiment 397, is an illegal genetic experiment created by Jumba Jookiba. He is designed to cause any two people zapped to constantly argue with each other. His one true place is making pro wrestlers fight more convincingly. Spats is voiced by Frank Welker.

Bio
Experiment 397 was the 397th genetic experiment created by Jumba with Hämsterviel's funding. He was designed to cause any pair zapped to constantly argue with each other.

397 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 397's pod landing in the window of Jumba and Pleakley's ship.

Lilo & Stitch: The Series
When the Proud Family arrives in Kauai for a visit, Jumba and Pleakley invite them to stay at their makeshift hotel called "Jumba & Pleakley's Bed & Not Breakfast." Suga Mama and Penny Proud marvel over the inside of Jumba's ship/hotel. Later, Suga Mama soaks herself in a hot tub bubble bath, while her dog Puff sleeps on a throw rug.

Meanwhile, a squirrel appears inside one of the windows of Jumba's ship and discovers 397's experiment pod. The squirrel mistakes the pod for a nut and attempts to eat it. When it finds out it could not eat the pod, the squirrel throws it into a bowl of bath bombs. Shortly after, Suga Mama reaches for another bath bomb, but takes out 397's pod instead. Mistaking the experiment pod for a bath bomb, Suga Mama drops the pod into the bathtub, activating 397. 397 then zaps the squirrel and Puff, causing the two animals to fight.

Sometime later, 397 causes mischief around town by zapping many pairs who end up fighting with each other. His victims include Oscar and Trudy Proud, BeBe and CeCe, Jumba and Mr. Cooper, Lilo and Penny Proud, and Gantu and Suga Mama. Stitch remains the only one to not be zapped by 397's argument ray. After making a vain attempt to break up Penny and Lilo's conflict, Stitch chases after 397. However, 397 manages to evade Stitch and eventually hitches a ride in the back of a jeep that Jumba and Mr. Cooper are driving, while they bicker with each other. 397 teases Stitch when he is unable to catch up with the jeep.

Later, Stitch tracks 397 down to a wrestling match, where the two face off on the roof of the arena. After a long battle between both experiments, 397 falls off the roof and into Penny's arms. She is angered by 397's presence at first, but after noticing the experiment's cuteness, she starts to soften up. When Penny tries to talk to Lilo, the latter still wants to fight with her. Fortunately, Penny manages to resist her urge to fight by counting to ten and then convinces Lilo to do the same, which she does.

After Lilo and Penny make up, the former relieves the other brawling pairs by telling everyone through an overhead microphone to count to ten after Gantu, who has been wrestling with Suga Mama the whole time, went down for the count. 397, named Spats, is then saved from Gantu, who has been after the experiment and tried to take Spats away from Penny at one point.

The next day, Lilo and Stitch find Spats a one true place with Wizard Kelly. He uses Spats to make his international wrestlers fight more convincingly. Penny mentions to Lilo about having a perfect report to write for her school, and she, along with the rest of the Proud Family, leave on good terms.

Leroy & Stitch
The first 624 experiments, including Spats, were round 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.

Spats participated in the following battle between the experiments 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 `Oe, which caused the Leroy army to shut down due to the original Leroy's failsafe.

Personality
Sneaky, clever and sly, Spats will do whatever it takes to cause a fight. He loves to cause a ruckus and provoke a fight even without using his abilities. He's a good actor and does a great job of faking being innocent and cute to get what he wants or to trick people. He's about as close to a flirt as an experiment can get. He also likes to tease and rub people's losses at his hands in their faces.

Trivia

 * Spats' pod color is yellow.
 * Spats is described by the experiment computer sceen as, "Experiment 397 Primary function: Argument instigator."