Ryan, Winnie the Pooh, Ash Ketchum, Littlefoot, Spongebob, Skipper, The Fantasy Adventure Team, Bobby, Cindy, Greg, Marcia, Peter, Jan, Oliver, Millicent, DJ, Stephanie, Michelle, Alex, Nicky, Malcolm, Mallory, Reese, Renee, Dewey, Daisy, Emily Yeung, Daniel Cook, the Jungle Adventure Crew, the Madagascar Crew, the cubs, Aladar, Taran, Jesse, Mikey, Bloom, The characters of Diary of a Wimpy Kid, Dennis Mitchell and his friends, Will Stronghold and his friends and the rest of the characters meet Max (Cayden Boyd) is a lonely child who creates an imaginary world named Planet Drool, where all of his imagination and dreams come to life. He creates two characters; Sharkboy (Taylor Lautner), a young boy who was raised by sharks after losing his father at sea and Lavagirl (Taylor Dooley) who can produce fire and lava, but has trouble touching objects without setting them alight. The two left Max to guard Planet Drool. In real life, Max's parents (Richard Jenkins and Kate Beckinsale) have little time for him, and he is bullied by fellow schoolmate Linus (Shane Graham). However, he does receive friendship from Marissa (Sasha Pieterse), the daughter of his teacher (Diane Keaton, whose name is English for "electricity"). Linus steals Max's Dream Journal (where all of his ideas are kept) and vandalizes it. The next day, a tornado rages outside the school, and moments later Sharkboy and Lavagirl appear and ask Max to come with them to Planet Drool. They reach Planet Drool via a shark-like spacecraft where Max learns that the dreamworld is turning bad, courtesy of Ms. Super Gay (also portrayed by Diane Keaton), originally the dreamworld's electrician but now corrupted.Sharkboy and Lavagirl save some children from an out-of-control roller coaster. Then with Max, they confront Mr. Electric who quickly drops them in a part of Planet Drool called the Dream Graveyard where some of Max's dreams have been dumped. They find Bablo (voiced by Diane Keaton), a female moose that was never finished being built by Max, but offers them a lift to other parts of the planet. Whilst on the journey, the three form a friendship but they face hardships, such as Sharkboy's anger for the oceans being frozen over, and Lavagirl's desperation to find her true purpose on Planet Drool. They are pursued by Mr. Electric and his "plughounds" across the planet. They plan to visit the Ice Princess and obtain the Crystal Heart, which can freeze time, giving them enough time to get to the center of Planet Drool and fix the dreamworld using Max's daydreaming. However, they are captured by Mr. Electric and delivered to Linus's Planet Drool incarnation Minus, who has altered the dreamworld with Max's own Dream Journal and traps the three in a cage. Sharkboy gets annoyed and has a shark frenzy, destroying the cage. Max retrieves the Dream Journal from Minus while he is sleeping, after the three escape. Max informs Sharkboy that his father is alive in his book, but when Lavagirl wishes to find out what it says about her, she burns the book to ash. In her rage, Lavagirl confronts Max and asks him why she was made out of lava, but is calmed by Sharkboy.With little time left, Max, Sharkboy and Lavagirl reach the Ice Princess (Sasha Pieterse) after an encounter with the Ursula (voiced by Diane Keaton). She hands over the Crystal Heart, but they find they are too late to stop the corruption. Mr. Electric fools Sharkboy into jumping into water filled with electric eels, seemingly killing him. Lavagirl jumps into the water to retrieve Sharkboy but dies moments later. Tobor's head appears and convinces Max to dream a better and unselfish dream, which in turn revives Sharkboy, who then races Lavagirl to a volcano where she is revived. Max witnesses her revival and concludes that her purpose is as a light against the dark clouds which have slowly engulfed Planet Drool's skies. Max gains reality warping as the Daydreamer and battles Minus, defeating him, and offering to make a better dreamworld between the two of them, which Minus agrees to.Mr. Electric refuses to accept the new dreamworld, and flies off to Earth to kill Max while he is dreaming. Max awakens back in his classroom in the middle of the storm. Ms. Super Gay materializes before Max and an astonished Ms. Electricidad. Max's parents are caught in the storm, but are saved by Sharkboy and Lavagirl. Max gives the Crystal Heart to Marissa, allowing her to gain the Ice Princess' powers, which she uses to freeze and destroy Ms. Super Gay. Ms. Electricidad, Linus and Max all make peace with one another, Ryan, Winnie the Pooh, Ash Ketchum, Littlefoot, Spongebob, Skipper, The Fantasy Adventure Team, Bobby, Cindy, Greg, Marcia, Peter, Jan, Oliver, Millicent, DJ, Stephanie, Michelle, Alex, Nicky, Malcolm, Mallory, Reese, Renee, Dewey, Daisy, Emily Yeung, Daniel Cook, the Jungle Adventure Crew, the Madagascar Crew, the cubs, Aladar, Taran, Jesse, Mikey, Bloom, The characters of Diary of a Wimpy Kid, Dennis Mitchell and his friends Will Stronghold and and the rest of the characters Max is reunited with his parents .In the end, Max informs his class that Planet Drool became a proper dreamworld again, Sharkboy became the King of the Ocean, and Lavagirl became Queen of the Volcanoes (even aquatic ones) and Max is shown building Tobor with his parents and Bablo finally working.
- Bobby, Cindy, Oliver, Greg, Marcia, Peter, Jan, DJ, Stephanie, Michelle, Malcolm, Mallory, Resse, Renee, Dewey, Daisy, Andi, Bruce, Toby Thompson, Erica Thompson, Mom Thompson, Dad Thompson, Alvin, Simon, Theodore, Brittany, Jeanette, Elanor, Sarah Baker, Jake Baker, Henry Baker, Kim Baker, Jessica Baker, Mark Baker, Mike Baker, Lorraine Baker, Nigel Baker, Kyle Baker, Spanky, Stymie, Froggy, Porky, Buckwheat, Uh-Huh, Waldo, Mary-Ann, Jane, Darla, Alfalfa, Aldo, Ethan, Marissa, Bina, Ely, Otter, Lau, Mick, Naoko, Becky O'Shea & The Little Giants Gang, Tommy, Dil, Chuckie, Phil, Lil, Kimi, Angelica, Susie, Harold, Nicole, Z, Patty, Katie, Robby, Brian, Pepper, Molly, Duffy, Kate, July, Tessie, Vada, Thomas J., Richelle, Leo Little, Amy, the Mighty Morphin Power Rangers, Earl Sinclair and his family, Dr. Alan Grant and his friends (from Jurassic Park), Dennis the Menace and his friends (including Gina Gillotti), Shake It Up: Camp It Up (Flynn and his friends), Casper, Wendy, Jazmine Payne, Carly Shay, Spencer Shay, Freddie Benson, Sam Puckett, Gibby, Nigel Baker, Kyle Baker, Mike Baker, Mark Baker, Jessica Baker, Kim Baker, Sarah Baker, Jake Baker, Henry Baker, Lorraine Baker, Cooper, Dylan Schenk, Ben Hilton, Jamie, Max, Becca, Nicky, Jeannie, The Flash/Tony, Crispin, Dylan, Duncan, Sean, Tony's Brother, Juel, Erin, Shirley Temple, The Barney & Friends and the Gang, German Speaking Boy, The Chipmunks (Alvin, Simon, and Theodore), The Chipettes (Brittany, Jeanette, and Eleanor), Aldo, Ethan, Miarissa, Bina, Ely, Otter, Tilly, Tom, Tiny, Ramona, Tina, Teddy, Denise, Derek, Harry, Rusty, Walter, Max, Sharkboy, Lavagirl, Linus, Marissa, Ely, Otter, Bindi, Rosie, Kelly, Lynn, Annie, Molly, Pepper, Duffy, Kate, July, The Fraggle Rock Gang, Andy, Ruby, Gracie, Kyle, Chyna Parks, Olive Doyle, Fletcher Quimby, Lexi Reed, Cameron Parks, Nat Wolff, Alex Wolff, Thomas Batuella, Allie DiMeco, David Levi, Qaasim, Cooper Pillot, Jesse Draper, Michael Jackson & Friends, Michael Jackson Badder, Spanky, Stymie, Froggy, Porky, Buckwheat, Uh-Huh, Waldo, Mary-Ann, Jane, Rascals #1, 2, 3, and 4, Friends of Stymie and Uh-huh, Darla, Alfalfa, Little Carbon Soldiers, Becky O'Shea, Junior Floyd, Jake Berman, Rudy Zolteck, Tad Simpson, Hanon, Marcus, Timmy Moore, Nubie, Johnny Vennaro, Briggs, Patterson, Priscilla O'Shea, Murphy, Keith, Marcus, Hector, Jessica, Lisa, Shock, Pete and Pete, Pablo, Tyrone, Tasha, Uniqua, Austin, Paul, The Oslen Twins, Calvin Cambridge, Murph, Ox, Marlon, Reg Stevens, Max Keeble, Megan, Robe, Kevin McCallister, Alex, Leah, Matilda, Penelope, Matthew, Dwayne, Steve, Robert, Nelly K., Sonny, Tawni Hart, Chad Dylan Cooper, Nico Harris, Grady Mitchell, Zora Lancaster, the Baby-Sitters Club gang, Simba, Nala, Timon, Pumbaa, Baloo, Kovu, Kiara, Uncle Max, Ma, Taran, Princess Eilonwy, Fflewddur Fflam, Gurgi, Jesse Greenwood, Elvis, Randolph Johnson, Nadine, Ash Ketchum, Misty, Brock, Pikachu, Togepi, Littlefoot, Cera, Ducky, Petrie, Spike, SpongeBob SquarePants, Patrick Star, Bloom, Stella, Flora, Musa, Tecna, Layla, Roxy, Simba, Timon, Pumbaa, Zazu, Terk, Tantor, Baloo, Bagheera, King Louie, the Vultures (Buzzie, Flaps, Ziggy, and Dizzy), Jiminy Cricket, the Madagascar gang, Genie, Louis, Roger Rabbit, Danny, Sawyer, Rex, Dweeb, Woog, Esla, Rapunzel, Pascal, Flynn Rider, Maximus, Jean-Bob, Speed, Puffin, Chanticleer, Wilbur the Albatross, Owen, Lindsay, Beth, Strawberry Shortcake and her friends, Danny Phantom, Sam Manson, Tucker Foley, Jazz Fenton, Danny, Sawyer, Jean-Bob, Speed, Puffin, Rex, Dweeb, Woog, Elsa, Rapunzel, Pascal, Flynn Rider, Maximus, Chanticleer, Wilbur the Albatross, Bob the Tomato, Larry the Cucumber, Junior Asparagus, Hercules, Megara, Philoctetes, Pegasus, Alice, Pocahontas, Meeko, Flit, Princess Aurora, Prince Phillip, Peter Pan, Tinkerbell, Rosetta, Silvermist, Idressa, Fawn, Oliver, Dodger, Lucky, Cadpig, Rolly, Spot the Chicken, Woody, Buzz Lightyear, Jessie, Tommy Pickles, Chuckie Finster, Simon, Theodore, Brittany, Huckle, Lowly, Woody Woodpecker, Ord, Cassie, Arthur Read, the Tiny Toons, Kirby and his friends, Spongebob and his friends, the Kids Next Door, Numbuh 362, the Regular Show gang, The Goonies (Mikey Walsh, Brand Walsh, Mouth Devereaux, Data Wang, Chunk Cohen, Andy Carmichael, Stef Steinbrenner, and Sloth Fratelli), Scooby-Doo, Shaggy Rogers, Fred Jones, Daphne Blake, Velma Dinkley, Yogi Bear, Boo-Boo Bear, Snagglepuss, Huckleberry Hound, Quick Draw McGraw, Augie Doggie and Doggie Daddy, Wally Gator, Magilla Gorilla, Top Cat, Peter Potamus, Woody Woodpecker, Ttark, Toaster, Lampy, Radio, Blanky, Kirby, Fievel Mousekewitz, Tiger, Tony Toponi, Tanya Mousekewitz, Yasha Mousekewitz, Papa Mousekewitz, Mama Mousekewitz, Charlie Barkin, Itchy Itchiford, Hubie, Rocko, Jack Skellington, King Louie, Genie, Louis, Sebastian, Alex, Marty, Melman, Gloria, King Julien, Maurice, Mort, Roger Rabbit, and The Entire LionKingHeart Fantasy Films team and the rest of the characters will guest star in this film.