One year after the defeat of the Syndicate, five months since the defeat of Denzel Crocker, six months since the defeat of Mojo Jojo, and 3 weeks after Mandark's defeat at the hands of Dexter, as Aku reforms the Syndicate after his crushing defeat with Jack, as he teams up with Gaston, Frollo, Oogie Boogie, King Koopa, Azula, Syndrome, Shere Khan, Rasputin, The Terrible Trio, Team Rocket, Zurg, Stinky Pete, Dr. Faciller, The Red Guy, etc. As they have returned of their revenge against the heroes of the MultToonVerse. As they plan to break a certain someone out of juvenile hall with the help of a certain diesel engine and a megalomaniacal penguin.
So, it is up to Spongebob, Jimmy, Timmy, Danny, Dexter, Jack, The Powerpuff Girls, and more to stop this new alliance before they break the spoilt foe out of juvie.