The Mermaid Princesses find themselves up against yet another enemy, and when all seems lost, by chance they gain the power to team up with the mightiest of heroes, the Avengers. Now with the Avengers by their side, the mermaids must use the DISKs to put a stop to this new threat.

When the World of Trophies is under danger of Subspace, Phineas and Ferb and their friends, and the other Smashers of Super Smash Bros. Brawl, must fight to save this world.

During show-and-tell at Maze High School, Sir Cumference makes a guest appearance, show off his new inter-dimensional portal, which accidentally bring Phineas and Ferb, and their friends while they were planning on ghost hunting, into Pac-World. But unfortunately, Betrayus sees everything with a hidden slug-cam and decides to invade Earth.

Phineas and Ferb have built a portal to travel to other universes, which happens to be Earth Land, Fairy Tail's main universe. Also, coincidentally Doofenshmirtz also ends up in Earth Land, and teams up with an old enemy of Fairy Tail.

When the Black Z-Rays hit the Chaos Emeralds, it sends Sonic, his friends, and Eggman to New Townsville. But later, the heroes learn that there was another Black Z-Ray that brings back one of Sonic and his friends' old enemies.

When Mojo Jojo's latest evil scheme to destroy the Powerpuff Girls fails, he and the PPG are sent to the world of PPGZ. At there, Mojo meets his own counterpart, and they round up the villains to take over both worlds.

Eggman has once again collected all 7 Chaos Emeralds, and Chaos Control is unleashed, but instead of going to Chris's world, it sends them to a whole new Earth, with different people that neither side knew existed. If there's people in this Earth that can help them return to Mobius, it's Phineas and Ferb.