One possible plot could be that the villain recruiters target a young and impressionable character from a new Disney story. They try to convince this character that the villainous way is the path to power and freedom. For example, they might offer the character magical abilities in exchange for joining their ranks. The story could then follow the character's internal struggle between good and the allure of the villains' offers.
Maleficent would be a great character to include. Her powerful magic and commanding presence would add a lot to the story. She could be either a recruiter or a target of the recruiters. If she were a recruiter, she could use her intimidation tactics to persuade others. If she were a target, it would be interesting to see how she fends off the recruiters, as she is not one to be easily swayed.
A plot could involve a spell gone wrong in the Inuyasha world that opens a portal to the Disney realm. Kagome, being from a more modern world, recognizes some of the Disney elements. Mickey Mouse could be the first Disney character they meet. He helps them navigate this new world while Inuyasha is trying to find a way back home. Meanwhile, Disney villains might see Inuyasha as a threat and try to get rid of him. But Inuyasha, with his combat skills, manages to fend them off. In the end, they find a way to close the portal and return home, but not before creating some new friendships and memories.
Perhaps in the crossover fanfiction, Hercules travels to the world of 'The Little Mermaid'. He meets Ariel and together they face a threat to both the land and the sea. Hercules could use his strength to protect Ariel while she uses her knowledge of the underwater world to help them navigate through various challenges. It would be a great combination of two very different Disney universes.
One idea could be having Maleficent and Ursula team up. Maleficent could use her dark magic to help Ursula get more powerful in the ocean realm. Maybe they plot to take over both the land and the sea. They could start by causing chaos in the kingdoms near the shore, like making storms and scaring the fishermen.
The plot could involve the female villain saving Deku from a dangerous situation. She might be in the right place at the right time and use her villainous powers for good in that instance. This would then start a chain of events where Deku is curious about her motives, and she has to keep her true nature hidden while getting closer to him.
It could center around the son of a villain who discovers a miraculous of his own. This miraculous might be different from the ones Ladybug and Chat Noir have. He then has to learn how to use it while also dealing with the fact that his family is against the heroes. His journey could be about finding his own identity, whether he wants to follow in his family's footsteps or become a hero in his own right. He may also face challenges from other villains who don't trust him because of his family ties.
One possible plot could be that Adrien discovers some dark secrets about his family or the superhero world. Maybe he feels betrayed by Ladybug or the other heroes. This disillusionment could push him towards the dark side. For example, if he finds out that his father was a victim of the so - called 'good' superheroes' actions in the past, he might want revenge.
In a 'Danny Phantom becomes villain' fanfiction, it could be that Danny has a major falling out with his friends and family. He feels betrayed and abandoned. This emotional turmoil causes him to snap and turn to the dark side. He then uses his ghost powers to take revenge on those who he thinks have wronged him, becoming a feared villain in the process.
Maybe the Gargoyles get accidentally transported to Bonkers' world. And they have to find a way back while dealing with all the chaos there.
One possible plot could be that the Disney villains somehow end up in the Naruto universe. For example, Maleficent could team up with Orochimaru. They might share their knowledge of dark magic and cause chaos in the Hidden Leaf Village. The ninjas would have to figure out how to deal with this new kind of threat that combines the deviousness of Disney villains with their own ninja - world problems.