I got ideas for Kingdom Hearts
For Final Fantasy: I've got Maenad and Shuyin in the game and they're lead by none other than Professor Ratigan.
In the game idea I thought of Kairi goes searchs for her mother the queen of Radiant Gardens and she gets help from Sora, Donald, Goofy, Riku, King Mickey and Basil of Baker Street.
There are two more addtional worlds in Radiant Gardens beside the 100 Acre Woods and Space Paranoids, there's Toon Town from Who Framed Roger Rabbit and inside the castle is the magic wardrobe that leads to Narnia in The Chronicles of Narnia: The Lion, The Witch and the Wardrobe.
They go to the Isle of Naboombu, the town from Toy Story they go as toys there "Like Sora as an action figure and Kairi as a doll", Ant Island from A Bug's Life they go as bugs there "Like Sora as an ant and Kiair as a butterfly" and Prydain from The Black Cauldron. It would be so cool having heartless getting led by the Horned King.
They also meet characters from classic Live-action movies like Captain Nemo from 20,000 Leagues Under the Sea, Mary Poppins and Herbie the Love Bug
Ideas for summon are Buzz Lightyear (flies, hits and shoots lazer), Herbie (like doing tricks car-like Heartless do), Aladar from Dinosaur, Elliot from Pete's Dragon, and Mr. Toad from The Adventures of Ichabod and Mr. Toad with his furious driving used on the enemies and there still is Genie from Aladdin
What if Disney put the world of Wreck-It Ralph into Kingdom Hearts like Wreck-It Ralph got into the game Kingdom Hearts for the game was in Litwak's Arcade and Wreck-It Ralph telling Sora and the gang Kingdom Hearts was a video game and Sora and the gang go into Game Central Station, and the games, Fix-It Felix, Jr., Hero's Duty and Sugar Rush?
I have an idea. Sora and the gang going to the world of Dick Tracey. Like have Big Boy be a boss and be a Heartless leader (thanks to the darkness in his heart). And with that, Tracey could be a hero who helps Sora fight like Aladdin, Beast, Peter Pan, Jack Skellington and Captain Jack Sparrow.