The first season takes place between the events of Season 3 from The Epic Tales of Captain Underpants and The Spooky Tale of Captain Underpants Hack-A-Ween. Most of the TV actors reprise their roles as the Toiletastics, the M.I.S.F.A.R.T.S., the teachers, and Lavatore Ree, while Rebel Wilson voices Misty Meaner. Unlike The Epic Tales of Captain Underpants, Sophie One and Other Sophie can speak, being voiced by Grey DeLisle and Kari Wahlgren. Every season has 26 episodes, and each episode has two segments (one focusing on the Toiletastics, one focusing on the M.I.S.F.A.R.T.S.).
Unlike The Epic Tales of Captain Underpants, instead of George and Harold making comics, the comic books must have Erica Wang's storytelling and Gooch's drawings. All Toiletastic segments must have villains to fight with, while all M.I.S.F.A.R.T.S. segments must have adventures around the world. Mr. Ree's brother, Lavatore, and Mr. Meaner's sister, Misty, joined the school after Season 3. The show will have four seasons and a musical special.