Nicktoons: Battle for Volcano Island (also known as SpongeBob and Friends: Battle for Volcano Island in Europe), is the sequel to the video game Nicktoons Unite! Players assume the role of up to 6 playable characters from numerous Nickelodeon shows, such as Danny Phantom, and The Fairly Odd Parents. The plot involves Danny Phantom, Timmy Turner (with Cosmo and Wanda), Patrick Star, Sam Manson, and Sandy Cheeks to protect the island from an all-new villain named Mawgu.
Tucker Foley, Squidward Tentacles, and Jimmy Neutron also appear, but only as support and are non-playable.
The game begins almost a year after Danny, Timmy, Jimmy and SpongeBob stopped the Evil Syndicate. When a far away island called Volcano Island is in danger, three crabs get together and perform a summoning to call The Nine to free their land from a creature called The Mawgu. When he overhears and attacks, he disrupts the summoning and all Nicktoons are scattered to parts of the island. However, two of the Nicktoons Danny Phantom and SpongeBob SquarePants have arrived at the Summoners Rock together. Then a crab Wizard known as The Wise Old Crab explains what's been happening and why they were summoned. Now, Danny and SpongeBob must travel together to reach their base camp area.
Upon learning the basics from the Wise Old Crab, SpongeBob and Danny run into Patrick bouncing on a diving board. Patrick joins them and the three continue on to a shipwreck on a cliff. After crossing the shipwreck, they find Danny's friend Tucker being attacked by seagulls. They eventually save him. Tucker questions Danny about the whole situation and the Wise Old Crab finally finds a safe spot to build their camp.
In the camp, the Wise Old Crab tells the whereabouts of the "Night Girl" (Sam) and the "Whiny Cephalopod" (Squidward). The heroes venture to a nearby lagoon where they find Sam fighting the sand monsters in the Fenton Peeler Suit. Sam mentions a weird noise on the other side of the lagoon and the heroes investigate to find a clarinet sticking out of the sand. SpongeBob knew right away that it was Squidward and pulls the clarinet freeing him. Squidward makes a sarcastic remark afterwards.
Back at the camp, the Wise Old Crab tells the location of the "Three-Headed Boy" (Timmy and his Fairies) to be found in an armed fortress filled with exile crabs. After crossing the dense jungle, the heroes reach the fortress, being attacked by numerous crab soldiers as they infiltrate. They find Timmy, Cosmo and Wanda leading a parade of crabs and it is revealed that they are actually being held captive. The heroes then head to the main gate to free Timmy and escape. After freeing him, Timmy finds a Jimmy Neutron communicator however, it is lacking a battery so the heroes were unable to communicate with Jimmy.
Back at the camp, SpongeBob and Danny find a crab villager in desperate need of help. His village is being attacked by a giant sand monster called "The Great Carrapace." They then head to the village and defeat the sand monster. The Wise Old Crab awards them with a jewel which happens to be the communicator battery. They finally made contact with Jimmy Neutron (still in Retroville) and he tells them that the Mawgu is using a dimensional rift to harness energy from all of their homeworlds which would eventually lead to their destruction. Jimmy gives the heroes the blueprints to the Neutron Rip Zipper (a machine that will drain the Mawgu of its power). The heroes now must search the island for parts.
The Wise Old Crab tells the location of the last hero, the "Deep Sea Squirrel" (Sandy). They head out to an ancient ruins to find Sandy in a scuffle with the rock monsters. After helping her out, Tucker informs the group that a Rip Zipper part is nearby. Sandy finds the part behind a crystal wall and breaks it along with SpongeBob with their karate skills. Sandy then questions them of whats going on. After Patrick's long story of him "jumping," Sam finally tells her that they must save the universe.
At the camp, the Wise Old Crab desperately tells the heroes that the queen of the Myrmecs have been kidnapped by the Florian tribe and being held captive at an oose mine. The heroes head out and free the queen from her captors. Jimmy also informs another Rip Zipper part is found nearby and the heroes collect it. Back at the camp, the Queen tells the heroes that the Florian tribe leader King Gorge build a dam to stop the water flowing through their village and now their forced to drink the ooze, making them slaves to the Mawgu.
The heroes confront King Gorge. Sam begs him to stop but King Gorge refuses. As the heroes fight him, the Myrmecs start chipping away at the dam and it finally collapses. The water converts King Gorge back to his original self, awarding them with the final part of the Rip Zipper.
Now the heroes finally set out to the Mawgu's lair, the volcano. After reaching the summit, they confront the Mawgu and follow him to the dimensional rift above. The other heroes distract him while SpongeBob and Danny scale the debris floating through the rift. SpongeBob and Danny finally battle him and use the Rip Zipper to drain him of his power. After that, Tucker opens a portal which sucks the Mawgu and sealing him for good.
After the battle, Jimmy activates a portal for the heroes to go home. The Wise Old Crab (his true name Shelly) and the Myrmec Queen thank them for their help. After the heroes leave, the camera then zooms to a cliff where the heroes faces are carved to honor them.