Pooh's Adventures of Mad Monster Party is another upcoming Winnie the Pooh crossover film planned to be made by Daniel Esposito and TheAngryPepe. It will appear on Dropbox as part of the quadruple feature with the remake version of Pooh's Adventures of It's the Great Pumpkin, Charlie Brown, Pooh's Adventures of Scooby-Doo! The Mystery Begins, and Winnie the Pooh Meets Coraline (co-directed by LegoKyle14) in October 2018.
Baron Boris von Frankenstein (voiced by Boris Karloff) achieves his ultimate ambition, the secret of total destruction. Having perfected and tested the formula, he sends out messenger bats to summon all monsters to the Isle of Evil in the Caribbean Sea. The Baron intends to inform them of his discovery and also to reveal his imminent retirement as head of the "Worldwide Organization of Monsters." Besides Frankenstein's Monster (referred to as "Fang") and the Monster's more intelligent mate (voiced by Phyllis Diller) who live in the island castle with Boris, the invites also include Count Dracula, the Mummy, Quasimodo (referred to as "The Hunchback of Notre Dame"), the Werewolf, The Invisible Man, Dr. Jekyll and Mr. Hyde, and the Creature from the Black Lagoon (referred to as the "Creature").
The Baron's beautiful assistant Francesca (voiced by Gale Garnett) enters the lab to confirm that all invitations have been delivered, and inquires about one of the addressees named Felix Flanken (voiced by Allen Swift). Frankenstein explains that Flanken is his nephew and successor in the monster business. This displeases Francesca, who covets the role for herself. Francesca asks why there wasn't an invitation for "It." Boris replies that "It" wasn't invited since "It" can be a crushing bore, explaining that "It" even crushed the island's wild boars in his bare hands the last time "It" was invited.
Frankenstein has his zombie butler Yetch (Swift impersonating Peter Lorre), Chef Mafia Machiavelli, and the zombie bellhops and servants make preparations for the upcoming party. The monsters begin to arrive on the freighter that Felix is also traveling on.
However, when Felix proves to be an incompetent, asthmatic (and unsuitably kind-hearted) human, the monsters plot to eliminate him and gain control of the secret formula! Over time Francesca develops feelings for Felix, after he unknowingly saves her multiple times. As Dracula, Frankenstein's Monster, and the Monster's Mate descend upon Francesca, she sends out a letter (via carrier bat) to an unknown recipient. When the monsters corner Felix upon capturing Francesca, they are frightened at the arrival of "It" (revealed to be a giant gorilla who is a take-off of King Kong) who proceeds to go on a rampage since he wasn't invited. "It" snatches up the monsters and Francesca (whom "It" develops a crush on).
Felix rushes off to tell his Uncle Boris what happened, and is instructed to head to the boat. Boris leads the zombies in rescuing Francesca from "It" using biplanes. Boris convinces "It" to let Francesca go and to take him instead. "It" complies, releasing Francesca. Felix and Francesca manage to get off the island as Boris and the remainder of the monsters remain in the clutches of "It." Displeased that the monsters tried to steal the secret of total destruction for themselves and attempted to kill Felix as well as having to put up with "It," Boris sacrifices his life by dropping the vial containing the formula, destroying the Isle of Evil and every monster on it.
The destruction is witnessed offshore by Felix and Francesca. Francesca tearfully admits to Felix that she is not human, but is in fact a robot creation of Boris von Frankenstein. Felix answers that "none of us are perfect"—mechanically repeating the words "are perfect," indicating that he has also been a robot creation of his uncle all this time.
- Ash Ketchum, Pikachu, Misty, Togepi, Brock, Simba, Nala, Timon, Pumbaa, Littlefoot, Cera, Ducky, Petrie, Spike, Chomper, Ruby, Guido, Grandpa Longneck, Grandma Longneck, Charlie Brown, Linus Van Pelt, Lucy Van Pelt, Sally Brown, Schroeder, Peppermint Patty, Marcie, Violet Gray, Patty, Pig-Pen, Snoopy, Woodstock, Mickey Mouse, Pluto, Sora, Donald Duck, Goofy, Kairi, Riku, Terk, Tantor, Scooby-Doo, Shaggy Rogers, Daphne Blake, Fred Jones, Velma Dinkley, Bugs Bunny, Daffy Duck, Ronald McDonald, Sundea, Birdie, Grimace, Hamburglar, Tika, Franklin, the McNuggets, the Fry Kids, King Kunga, The Penguins of Madagascar (Skipper, Kolwalski, Rico, and Private), The Bowser Family, Azula, Psycho Rangers, Phantom Blot, One-Eyed Sally, Blather, the Ancient Minister and his Family, Jafar, Iago, Maleficent, Winterbolt, Myotismon, Scar, Shenzi, Banzai, Ed, Arthur and Cecil, Ichy and Dil, Dr. Facilier, Team Rocket, The Crime Empire, and The Sanderson Sisters will guest star in this film.
- This is an NTSC film with NTSC bits from the Winnie the Pooh films, The Jungle Book 1 and 2, Pinocchio, Mickey's Christmas Carol, Fun and Fancy Free, The Lion King films, The Emperor's New Groove, Kronk's New Groove, the Pokemon films, The Land Before Time films, the Peanuts films, the Mickey Mouse films, A Goofy Movie, Tarzan, the Scooby-Doo films, Space Jam, Looney Tunes: Back in Action, the Madagascar films, the Aladdin films, Sleeping Beauty, The Princess and the Frog, and Batman: Mask of the Phantasm.
- This film was originally planned to feature fan-made voice acting, but the acting was canceled since not many users agreed to voice certain characters.
- The Peanuts theme music Linus & Lucy (composed by the late Vince Guaraldi), You and I (which was featured in the end credits for Scooby-Doo! The Mystery Begins), Shaggy, Where Are You (from the 2002 live-action Scooby-Doo film), I'm in Love with a Monster from Hotel Transylvania 2, and the end credits music from Coraline (composed by Bruno Coulais) will be the end credits music for the quadruple feature with the remake version of Pooh's Adventures of It's the Great Pumpkin, Charlie Brown, Pooh's Adventures of Scooby-Doo! The Mystery Begins, this film, and Winnie the Pooh Meets Coraline.
- The Film is the Sequel to Sora Says Hocus Pocus and a Prequel to Sora's Adventures of Gilligan's Island Saga.
- This film was originally planned to be released in October 2015 to coincide with the 30th anniversary of The Black Cauldron, but ended up moved to October 2016, due to production delays with Pooh's Adventures of Fantasia. However, due to production delays with the remake version of the now-separate Winnie the Pooh's Search for The Black Cauldron, the film was then moved to October 2017 with the remake version of Pooh's Adventures of It's the Great Pumpkin, Charlie Brown preceding it. Thus, both films ended up being moved to October 2018 instead as part of a quadruple feature with Pooh's Adventures of Scooby-Doo! The Mystery Begins and Winnie the Pooh Meets Coraline (co-directed by LegoKyle14), due to production delays with PrinceJosh1992's spin-off film Sora Says Hocus Pocus.
- Reese Ambler originally planned to co-direct this film, but he permanently retired from the Pooh's Adventures League, so TheAngryPepe (who plans to ironically make Aqua, Terra, and Ventus' Adventures of Mad Monster Party) will co-direct this film instead.
- This will be Daniel Esposito's first crossover film to guest star the Peanuts gang.