The game begins with Bubbles and Yoshi conversing, seeing that a dark omen is going to befall on the Nicktoons Park. But Buubles sees a light among the darkness and feels there is still hope.
SpongeBob SquarePants has journeyed to a new Nicktoons Park with his best friend Patrick Star. Almost immediately they are introduced to the new and fascinating Play Park. Play Park is spoken as a place where the fun never stops. However, they find that the Nicktoons there really are trapped and cannot leave Play Park. A playful 6-year old Boo named MattBoo comes to the rescue before they too are bewitched, but Patrick ends up trapped after saving them. As they are transported back to the Nicktoons Park, SpongeBob is momentarily in Townsville, and Bubbles shares her knowledge of the impending doom, and informs SpongeBob that he can save the Nicktoons Park. After returning to the Canterlot Area, MattBoo and SpongeBob team up to solve the case and save the trapped Nicktoons. They seek out Twilight Sparle who opened a Paper Portal for them, so that they may learn how to open the portal. Once back in the park, they learn that ringing a Nick Bell will bring all the Nicktoons out of their trace. They manage to ring the bell and free all the Nicktoons in the Canterlot Area, and then decide to explore the other Areas to spread the word of the circumstances for entering the Play Park.
They venture to the Irken Area where they meet GIR. They later learn he is Invader Zim's idiotic, and hyperactive SIR assistant. They speak to Zim about the events in Play Park, and he recalls the old legend that a Death Void will appear when the two worlds begin to merge. GIR eventually decides to join their investigation and becomes their third member, after Zim tells him he'll give him tacos when he returns. They venture back into Play Park through the Paper Portal in the Irken Area where they meet Rocko Wallaby who wants to find his dog, Spunky. Spunky had been lead into Play Park, and never returned. Rocko said that he would go find Spunky himself, but he doesn't want to disappear too. They find Spunky as well as Patrick, and are met with the second in command: The Almighty Tallest. They allow them to ring the Nick Bell and successfully free the Irken Area, aware of the consequences. Patrick decides to stay behind so he can warn Nicktoons coming into Play Park before they are entranced and cannot leave.
The trio then make their way to the Dimmsdale Area where they meet Hoops and Yoyo who are looking for their friend, Spike the Dragon. They find Spike trapped in a cannon. MattBoo decides the best course of action would be to fire Spike out of the cannon. Once he makes a landing, he angrily storms towards the group and challenges to a battle as payback. Once he calms down, he states that being launched gave him an idea for his first attack, and mentions that he wants to enter the Battle Tournament and asks that his new friends join him. With Spike the official new member, they set out to ask the Area Keeper, Princess Celestia to accept their entry into the tournament. Once they've proven themselves, they are allowed into the tournament. In the first round, they battle against Shadow the Hedgehog. When he's beaten, he then escapes into the Paper Portal hidden in the Arena wall. They journey to the O-Town Area to investigate and find possible clues to the location of the Nicktorium. They then notice a small, black swirl in the sky, the death void Zim warned them about.
Upon arriving in the O-Town Area, they find that the Nicktoons are suspicious of outsiders, but quickly earn their trust after helping repair a broken bridge keeping a passenger train from returning to the depot. The Area Leader then suggests they check the warehouse. Rainbow Dash makes an entrance to the warehouse with a cloud, and the quartet explore inside. They witness Gary the Snail, Pac-Man 64, and Xsaviar fleeing a Duosion who explains that only the three of them can repair the elevator to the Nicktorium. After pleading with the three Nicktoons, they agree to fix the elevator for the player, and they finally enter the infamous Nicktorium. Once inside, they find Ami who proudly boasts that she invited the Paper Portals. But when she hears of the misfortune overcoming the Nicktoons Park, she instantly becomes concerned for LT Fan. She then repairs a Paper Portal in her van so that they may venture into Play Park and ring the final Nick Bell. With the final Bell rung, the four zones of Play Park connect into one mass, opening the portal to the Play Palace.
Inside the palace, the quartet are met by Kirby, possessed, who then attacks them. LT Fan then appears and erases MattBoo, GIR, and Spike's memories of SpongeBob, and sends SpongeBob into a nightmare. Patrick manages to find his way into SpongeBob's dream world and break him out of his nightmare. SpongeBob then sets out and finds his three friends and helps regain their memories. With their memories regained, they travel back to Play Park to challenge LT Fan. The gang defeat LT Fan.
And so, peace has returned to both the Nicktoons Park, and Play Park, thanks SpongeBob and his new pals.
- SpongeBob SquarePants (SpongeBob SquarePants)
- MattBoo (Matthew's World, The MattBoo Show)
- GIR (Invader ZIM)
- Spike the Dragon (My Little Pony: Friendship is Magic, Hoops and Yoyo and Spike)
Unlockable Extra Playable Characters
- Yoshi (The Adventures of Kirby and Yoshi) (Unlocked after the Canterlot Area is completed)
- Kirby (The Adventures of Kirby and Yoshi) (Unlocked after if you beat one level of PlayPalace with each starter character)
- Ami (Hi Hi Puffy AmiYumi, The Adventures of Kirby and Yoshi) (unlocked after the Dimmsdale Area is completed)
- U.B. (U.B. Funky, Gannon X) (Unlocked after the O-Town Area is completed)
- Invader Rob (The Invader Rob Show) (Unlocked after the Irken Area is completed)
- Y-Guy (Y-Guy) (Unlocked after the game is completed)
- SuperSaiyanKirby (SuperSaiyanKirby Adventures) (Unlocked after getting 100 combos in a boss level)
- Bubbles (The Powerpuff Girls)
- Patrick Star (SpongeBob SquarePants)
- Twilight Sparkle (My Little Pony: Friendship is Magic, Hoops and Yoyo and Spike)
- Invader Zim (Invader ZIM)
- Rocko Wallaby (Rocko's Modern Life)
- Spunky (Rocko's Modern Life)
- The Almighty Tallest (Invader ZIM)
- Hoops (Hoops&Yoyo, Hoops and Yoyo and Spike)
- Yoyo (Hoops&Yoyo, Hoops and Yoyo and Spike)
- Princess Celestia (My Little Pony: Friendship is Magic)
- Shadow the Hedgehog (MattBoo and Friends: Warriors Against LT Fan)
- Rainbow Dash (My Little Pony: Friendship is Magic, Hoops and Yoyo and Spike)
- Gary the Snail (SpongeBob SquarePants)
- Pac-Man 64 (The Homestar Runner and Pac-Man 64 Show)
- Xsaviar (Matthew's World, The MattBoo Show)
- LT Fan (MattBoo and Friends: Warriors Against LT Fan)
Cameo Appearing Nicktoons
- Piddles (Hoops&Yoyo)
- Fluttershy (My Little Pony: Friendship is Magic, Hoops and Yoyo and Spike)
- Applejack (My Little Pony: Friendship is Magic, Hoops and Yoyo and Spike)
- Pinkie Pie (My Little Pony: Friendship is Magic, Hoops and Yoyo and Spike)
- Rarity (My Little Pony: Friendship is Magic, Hoops and Yoyo and Spike)
- Squidward (SpongeBob SquarePants)
- Doug Funnie (Doug)
- Ren Höek (The Ren and Stimpy Show)
- Stimpy (The Ren and Stimpy Show)
- Blossom (The Powerpuff Girls)
- Buttercup (The Powerpuff Girls)
- Yumi (Hi Hi Puffy AmiYumi)
- Chowder (Chowder)
- Meatwad (Aqua Teen Hunger Force/Aqua Unit Patrol Squad)
- Ignignokt and Err (aka The Moonintes) (Aqua Teen Hunger Force/Aqua Unit Patrol Squad)
- Pikachu (Pokemon, Hoops and Yoyo and Spike)
- Snivy (Pokemon, Hoops and Yoyo and Spike)
- Collector (SuperSaiyanKirby Adventures)
- Nicktoons Park (Training Area)
- Play Park (Mini Area)
- Canterlot Area
- Irken Area
- Dimmsdale Area
- O-Town Area
- Play Palace
- Play Park (Boss Area)
In the Wii version of the game, all four characters can be played at once. In the 3DS version of the game, the player has to choose one of the four characters.
When the Nick Bell is rang, the Nick slogan "Ni-ni-ni-ni-ni-ni-ni-Nick, Nickelodeon" is heard as the ring.