Experiment 031 was the 31st genetic experiment created by Jumba with Hämsterviel's funding. He was designed to run around and pinch people. 031 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. Against statistically unlikely (but not impossible) odds, several experiment pods landed in one location: Mrs. Hasagawa's yard, 031's pod being one of them.
At an unknown point, Mrs. Hasagawa mistook 031's pod for an apricot and placed it in a colander for later consumption along with numerous other pods.
After Lilo and Stitch redecorated Mrs. Hasagawa's yard without her permission, she was less than thrilled with the results, but decided to thank them for their work with the "apricots." The pods were then revealed, but before Lilo and Stitch could stop her, she washed them with a watering can, thus activating the experiments.
After his activation, 031 began to follow his primary function by pinching Lilo and exclaiming, "Got you!" Lilo and Stitch believed the experiments to be a danger to Mrs. Hasagawa and, along with Jumba and Pleakley, decided to capture them all. Eventually, Stitch wrestled with 031, the former winning, and forcing the latter into a container.
031 and the other experiments were about to be taken away, but were returned to Mrs. Hasagawa when Lilo and Stitch saw how much she cared for them. 031 was then named Gotchu.
In "Woops", Gotchu was oddly seen as one of the captive experiments in Hämsterviel's prison cell, although he is barely seen behind Fibber, suggesting Gantu caught Gotchu, but this was an error. Gotchu was then sent back to Gantu after Experiment 600 caused mischief and nearly blew Hämsterviel's cover to the prison guards.
Gotchu was one of the experiments that was gliding on the screen, but he is 586 instead of 031.
The first 624 experiments, including Gotchu, 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.
Gotchu participated in the following battle between the experiments and the Leroy clones by chasing and pinching Leroys.
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 ʻOe", which caused the Leroy army to shut down due to the original Leroy's fail-safe.
- According to Mrs. Hasagawa, Gotchu has a special neck pillow.
- In "Woops", Gotchu erroneously appeared with Gantu's other captive experiments, although he is barely seen, but he was captured by Lilo and Stitch, and Gantu was asleep during Gotchu's debut.
- Gotchu is one of the few experiments to not appear in the group photo at the end of Leroy & Stitch.