When and where does it show the clash of nicktoons?

You're likely thinking of Nicktoons Unite!, a video game released in 2005 for the PlayStation 2, Xbox, GameCube, and PC. It featured a crossover of various popular Nicktoons characters, including SpongeBob SquarePants, Jimmy Neutron, Danny Phantom, and the Fairly OddParents.

However, there is no movie, television show, or other media called "Clash of Nicktoons".

If you have more details about what you're looking for, like a specific year or any characters you remember, I might be able to help you find it!