Chalk Zone/The Fairly OddParents

Rudy as Timmy (with Penny as a Extra)

Shaggy & Velma (from Scooby-Doo) as Timmy's Parents

Numbuh 4 (from KND) as Cosmo

Numbuh 3 (from KND) as Wanda

Mandy (from The Grim Adventures of Billy & Mandy) as Vicky (both voiced by Grey DeLisle)

Dexter (from Dexter's Lab) as A.J. (both are smart)

Lazlo (from Camp Lazlo) as Chester