When Cosmo, Wanda, and Poof are captured and taken to Hugh J. Magnate Jr., Timmy Turner asks Chester and A.J. to give him a ride to Magnate's hideout so he can rescue them. They initially decline on helping him since they believe Timmy is still acting like a kid and not being serious, but Timmy manages to get them to agree by saying he'll wish for the two to find incredibly hot girlfriends.
Chester and A.J. are later seen with their new girlfriends at the very end of the movie, watching as Timmy and Tootie ride off into the sky in their "Wishful Thinking" van.