Experiment 255 was the 255th genetic experiment created by Jumba with Hämsterviel's funding. She was designed to make anyone sick with her obnoxious fumes. 255 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.
Mrs. Sickly is a light teal Mr. Stenchy-like experiment with golden eyes, puffier antennae and smaller hair.
Powers and abilities
Like Mr. Stenchy, Mrs. Sickly appears disarmingly cute to everyone else except other experiments and emits an extremely foul and noxious odor 48 hours after she is activated.
Mrs. Sickly was released by Dr. Hämsterviel with Mr. Stenchy during Christmas in Japan. This is when it is revealed that if the two are to come together, they have the power to destroy entire planets. This leads to Yuna, Pleakley, Stitch, Jumba, Hämsterviel and Gantu on a hunt to round up the clones of Mr. Sickly and Mr. Stenchy in order to save the world's Christmas, as Hämsterviel mass produced the clones and sold them to many children across Japan and the rest of the world.
- Mrs. Sickly is one of the rare experiments to have sclerae and pupils instead of solid black eyes, the others being Mr. Stenchy, Skip, Clink, and Nosox.