Ryan, Pooh, Ash, Littlefoot, Alex, Tai, Simba, Stan, Bobby Brady, Alvin, Spanky, Malcolm, and the rest of the gang) meet two unrelated young girls who happen to look identical and they suddenly meet. Amanda Lemmon is an orphan, and about to be adopted by a family whom she doesn't like, The Butkises. She actually wants her child-loving case worker Diane Barrows to adopt her instead. Diane would like the same thing but authorities will not let her, due to her low salary. Alyssa Callaway is coming home from her boarding school's piano recital competition, only to find that her wealthy father Roger is about to marry Clarice Kensington (whom Mr.Big, Agatha Trunchbull, Woim, Butch, The Bully Kids, the Bowser family, King Ghidorah, Plankton, Ozzy, Strut, Ichy and Dil, the Star Wolf team, the Predator, One-Eyed Sally, Blather, the Crime Empire, Kaput and Zosky and the Subspace Empire, and Bad Michelle work for) a socialite who (secretly) hates kids and baseball (which Roger adores). The girls switch apples and find out that Diane and Roger would fit together perfectly. So they arrange "chance" meetings with the desired result: They fall in love with each other. After some turbulences, Alyssa who poses as Amy ends up being adopted by the Butkises. She and Diane (while looking for Alyssa) find out the only reason The Butkises have adopted many children were for the children to work in their salvage yard. When Clarice secretly spies on Roger and Diane, she decides to move up the wedding from the next month to the next day. After Amy, who poses as Alyssa, proves to Vincenzo who she really is at the church, he summons to have the real Alyssa picked up from the Butkises' salvage yard to stall the wedding. Once Diane and Alyssa end up at the church, Roger stops the wedding and tells Clarice that he fell in love with Diane. Furious, Clarice slaps Roger and prepares to do the same to both Amy and Alyssa but is stopped by both Diane and Vincenzo. Clarice storms out of the church, embarrassed. Roger and Diane both find out in the end that it was Amy and Alyssa that arranged all the meetings between the two of them the entire time.
- Greg, Marcia, Peter, Jan, Oliver, Millicent, Aldo, Ethan, Spanky, Stymie, Froggy, Porky, Buckwheat, Uh-Huh, Susan Evers, Sharon McKendrick, Katie, Sean, Ash Ketchum, Pikachu, Misty, Togepi, Brock and the Pokemon gang, Simba, Nala, Timon, Pumbaa, Zazu, Kovu, Kiara, Ma, Uncle Max, Rafiki, Littlefoot, Cera, Ducky, Petrie, Spike, Chomper, Ruby, Guido, Grandpa Longneck, Grandma Longneck and the Land Before Time Gang, SpongeBob SquarePants, Patrick Star, Squidward Tentacles, Sandy Cheeks, Eugene Krabs and the gang, Bloom, Stella, Flora, Musa, Tecna, Layla, Stan Marsh, Kyle Broflovski, Eric Cartman, Kenny McCormick, Jean-Bob, Speed, Puffin, Terk, Tantor, Louis, Ray the Firefly, Genie, Iago, Sebastian, Baloo, Bagheera, King Louie, the Vultures, Jiminy Cricket, Mickey Mouse, Donald Duck, Goofy, Kenai, Koda, Rutt and Tuke, Fu Dog, Roger Rabbit, Woody, Buzz Lightyear, Charlie Barkin, Itchy Itchiford, Jack Skellington, Chanticleer, Owen, Izzy, Bob the Tomato, Larry the Cucumber, Junior Asparagus, Jimmy and Jerry Gourd, the Powerpuff Girls (Blossom, Bubbles, and Buttercup), the Rugrats Gang, Carly Shay, Sam Puckett, Alvin, Brittany, Bobby, Cindy, Oliver, Freddie Benson, Spencer Shay, Gibby, Popeye, Olive Oyl, Popeye's Nephews (Peepeye, Poopeye, Pipeye, and eakey, Jumba, Mario, Luigi, Princess Toadstool, Toad, Yoshi, Donkey Kong, Diddy Kong, SoPupeye), Scrooge McDuck, Huey, Dewey, Louie, Webby, Launchpad McQuack, Chip and Dale, Lilo, Stitch, Plnic the Hedgehog, Miles "Tails" Prower, Knuckles the Echidna, Amy Rose, Cream the Rabbit, Cheese the Chao, Shadow the Hedgehog, Rouge the Bat, Team Chaotix (Vector the Crocodile, Espio the Chameleon, and Charmy the Bee), Silver the Hedgehog, Blaze the Cat, Spyro the Dragon, Sparx the Dragonfly, Banjo and Kazooie, Barney the Dinosaur and the gang, Baby Bop, BJ, Riff, The Griffins (Peter, Lois, Chirs, Meg, Brian, and Stewie), Pocahontas, Meeko, Flit, Princess Aurora, Peter Pan, Tinkerbell, Terrence, Fawn, Rosetta, Silvermist, Iridessa, Vidia, Alice, Hercules, Phlioctetes, Pegasus, Phineas and Ferb, Isabella Garcia-Shapiro, Alex, Marty, Melman, Gloria, The Penguins of Madagscar (Skipper, Kolwalski, Rico, and Private), King Julien, Maurice, Mort, Taran, Princess Eilonwy, Fflewddur Fflam, Gurgi, Jesse Greenwood, Elvis, Randolph Johnson, Nadine, The Goonies (Mikey Walsh, Brand Walsh, Mouth Devereaux, Data Wang, Chunk Cohen, Andy Carmichael, Stef Steinbrenner, and Sloth Fratelli), Aladdin, Princess Jasmine, Abu, Yogi Bear, Boo-Boo Bear, Snagglepuss, Huckleberry Hound, Quick Draw McGraw, Augie Doggie and Doggie Daddy, Wally Gator, Magilla Gorilla, Top Cat, Peter Potamus, Scrooge McDuck, Huey, Dewey and Louie, Webby, Tom, Huckleberry, Becky, Scooby-Doo, Shaggy Rogers, Fred Jones, Daphne Blake, Velma Dinkley, Bugs Bunny, Daffy Duck, Woody Woodpecker, Ttark, Rex, Woog, Elsa, Dweeb, Fievel Mousekewitz, Tiger, Tony Toponi, Tanya Mousekewitz, Yasha Mousekewitz, Papa Mousekewitz, Mama Mousekewitz Simba, Huey, Dewey, Louie, Ash and the characters, Littlefoot and the characters, Spongebob and the characters, Scooby-Doo and his friends, Ronald McDonald and his friends, Ariel, Melody, Princess Jasmine, Belle, Princess Aroura, Princess Odette, Princess Tiana, Snow White, the entire cast from Regular Show, Meta Knight, Pajama Sam, Donkey Kong, Diddy Kong, Dr. Rabbit, Dr. Brushwell, the Star Fox team, the Kids Next Door, Numbuh 362 Kids World's Adventures Team, the Tiny Toons gang, Zeke, Waldo, Twin #1 & 2, Darla, Alfalfa, Chyna Parks, Olive Doyle, Fletcher Quimby, Lexi Reed, Cameron Parks, Bindi, Rosie, Malcolm, Mallory, Resse, Renee, Dewey, Annie, Molly, Pepper, July, Kate, Duffy, Alvin, Simon, Theodore, Brittany, Jeanette, Elanor, Vada, Thomas J., the Kids Mega Man Costume, the Baby-Sitters Club gang and lots more guest stars in this film.
- Mr. Big, Bad Michelle, Agatha Trunchbull, Woim, Butch, Marv, Harry, The Bully Kids, the Bowser family, King Ghidorah, Plankton, Ozzy, Strut, Ichy and Dil, the Star Wolf team, the Predator, One-Eyed Sally, Blather, the Crime Empire, Kaput and Zosky and the Subspace Empire will be working for the main adversary (antagonist) Clarice Kensington.