Jimmy Timmy Power Hour 2: When Nerds Collide! is the second Fairly OddParents/Jimmy Neutron cross over.
Needing a date for the school dance, Timmy Turner returns to Retroville, but this time he takes Cosmo and Wanda with him. There, Timmy meets Cindy Vortex, but a problem arises when he and Jimmy Neutron fight over who gets to take Cindy to the Friday the 13th Dance, and given the date, the Anti-Fairies are up to stop the Earth's rotation to make Friday the 13th last forever.
Professor Finbarr Calamitous wants to blow up the universe and after seeing Timmy's Godparents, he decides to go to Timmy's universe to get a fairy to help with his plan. He gets a fairy, ironically, Jorgen Von Strangle, the leader of the fairies.
In the Fairy World Prison, Anti-Cosmo attempts to bust his fellow Anti-Fairies out of prison, but Jorgen von Strangle has tightened security so that no one in that universe could have access to the prison...which gives Anti-Cosmo the idea of traveling to another universe to find someone. Meanwhile, in both their dimensions, Timmy and Jimmy are preparing for their own Friday the 13th dance parties, and they both want Cindy to be their "date".
Timmy travels back to Retroville to ask Cindy Vortex, right before Jimmy crashes into her room at the same time. The two suddenly begin to duel over who is the real genius. Professor Finbarr Calamitous is also watching the two battle in the skies from his mountain laboratory, and notices Timmy easily beating Jimmy with the help of his Fairy Godparents, Cosmo and Wanda.
Timmy takes Cindy back to Dimmsdale with him, using wishes to fulfill each of Cindy's desires. Jimmy, along with the rest of his friends, follow them to Dimmsdale.
Calamitous attempts to jump in with them, but notices Jimmy's lab is wide open and decides to go inside. He uses the hypercube to get to Dimmsdale. Jimmy ends up being mistaken for Timmy again, and ends up doing his chores while the real Timmy keeps trying to ask Cindy to be his date. He wishes that Cosmo and Wanda would give them whatever they wished to keep them out of his way while he asks Cindy out.
Calamitous and Anti-Cosmo meet up and, realizing they're both from separate dimensions, team up to bust the Anti-Fairies out from prison, which is when they head towards Dimmsdale. Anti-Cosmo double crosses Calamitous by locking him in the same cell as Jorgen, but when he leaves, the two easily escape since the key was left in the lock.
Jimmy interrupts Cindy and Timmy once again (while Cindy is obviously happy Jimmy made it), but then the three notice the anti-fairies swarming around the world, fulfilling their plan to cause bad luck every day by making the Earth still, making every day Friday the 13th. Both Timmy and Jimmy defeat the anti-fairies together, with the use of his hypercube (which Calamitous evidently dropped) and a fairy net (from Crocker's lab).
Timmy then find AJ's gene-splicer and accidentally shoots both Jorgen and Calamitous, merging them together and Calamitous trying to control Jorgen's magic for evil. To demonstrate his new powers Calamitous controls Jorgen's arms into smacking Jorgen's head with Jorgen unable to stop him. Calamitous uses Jorgen's body to capture Cindy, kill Timmy and Jimmy; and return to Retroville. The group mourns the deaths of Timmy and Jimmy but later they find that the blast actually turned them into snails because the magic does not allow deaths to be performed by a fairy king's magic if the king forbids it.
Timmy and Jimmy realize that the threatened fate is caused by their rivalry over Cindy and decide to settle their differences and form an alliance. Cosmo and Wanda turn the two back to kids and the group sets out to stop Calamitus.
Jimmy, Timmy and their friends go back to Retroville and see that Calamitous has built a giant "big bang bomb", which will allow Calamitous to recreate the world in his own vision. Attempting to force Jorgen to assist him Calamitous turns Cindy into a goldfish right as Jimmy and Timmy make it to the top of the bomb.
Timmy and Jimmy realize that Jorgen will be freed from being controlled by Calamitous if they break Da Rules. They break fairy rules such as using hot dogs as a rocket that flies and spits fire; using magic to fall in love; using magic to make a chicken fall in love with a human; using magic to win games such as "rock paper scissors"; and then using magic to wound someone.
Over this time Jorgen becomes infuriated with his rules being violated and is able to resist Calamitous' control enough for Jimmy to separate Calamitous and Jorgen apart back to normal. With 6 seconds left before detonation Jorgen confiscates the bomb and destroys it before it can blow them away.
The group then shrinks Calamitous and locks him up in an open bottle to punish him. Jorgen thanks them for their help and rewards them by assisting Cindy into joining Timmy and Jimmy at once in dancing their separate Friday the 13th parties.