SpongeBob acquires Mermaid Man's powers when he wears his belt. Unfortunately SpongeBob puts the Dirty Bubble into a washing machine, which causes him to split into countless dirty bubbles. SpongeBob has to stop villains such as Manray, The Sinister Slug, The Jumbo Shrimp, Atomic Flounder, and Dirty Bubble, using Mermaid Man's powers to save Bikini Bottom. The story is divided into Acts, each with a different villain trying to wreak havoc on Bikini Bottom such as Manray wants to flood Goo Lagoon, Sinister Slug's evil plan is to stop the talent show, Jumbo Shrimp with the help of Plankton creates a machine to shrink people the size of Plankton on top of the Sea Needle, The Atomic Flounder causes chaos in Industrial park and The Dirty Bubble returns to put the end of the Yellow Avenger with the machine the Jumbo Shrimp used in the third act and plans to hit SpongeBob with more Little Dirty Bubbles.
source: en.wikipedia.org/wiki/SpongeBob_SquarePants:_The_Yellow_Avenger