When Mertle reveals to Lilo that she is entering her "dog" Gigi (actually Experiment 007) in the Junior Dog Show in Honolulu, Stitch becomes annoyed by Gigi's yapping and swallows her whole. After Lilo pulls Gigi out of Stitch's stomach and gives her back, Mertle angrily calls both Lilo and Stitch "riffraff" and takes Gigi, now covered in slobber, to a pet salon to get her cleaned up.
Wanting to win Mertle's friendship by beating her "dog", Lilo travels to Honolulu with Jumba and Pleakley. When they arrive there, Lilo enters Stitch in the junior dog show as well, claiming that he is a rare blue-furred ectoplasmic detection dog, which impresses the judges somewhat. Lilo and Mertle engage in an unfriendly rivalry before entering Stitch and Gigi into all the competitions, and the contest takes place the next day while Jumba and Pleakley are busy going sightseeing. However, both Stitch's temper (when he fights with a contestant's dog after the latter sniffs him) and overconfidence cause him to lose the first two rounds. In the final competition, Mertle secretly gives Stitch extra strong coffee to make the latter go crazy so that Gigi would win.
Mertle's plan is successful at first, but then Gantu unexpectedly bursts into the building, looking for the experiment that Mertle has. Stitch attacks Gantu as he fires his plasma gun uncontrollably. However, a stray plasma blast causes the ceiling to collapse on top of Stitch. Gantu then grabs Gigi from Mertle. Mertle complains that Gantu took Gigi, but Lilo tells Mertle that they will save Gigi. Lilo then gives Stitch more coffee intentionally, enabling the latter to defeat Gantu and get Gigi back.
Grateful but indignant, Mertle gives the "Best in Show" trophy to Lilo, saying that she and Gigi don't need it anymore and that they already know that they are the best. However, Lilo and Stitch both seem to take it okay.