Cloudy, A.K.A. Experiment 320, is an illegal genetic experiment created by Jumba Jookiba. He is designed to depress others with constant rain. His one true place is raining on Mrs. Hasagawa's fruit, suggesting he may be one of her "cats".
Cloudy was seen early in the movie raining on Mrs. Hasagawa's fruit as Lilo was making her rounds with Scrump to make sure all the experiments were happy in the one true place they belonged.
Later, the first 624 experiments, including Cloudy, 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.
It is unknown whether or not Cloudy 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 ʻOe," which caused the Leroy army to shut down due to the original Leroy's fail-safe.