The new villain could be a former student of the Nutty Professor who felt wronged in some way. Maybe the student was expelled unfairly (in his mind) or didn't get enough credit for his contributions to a project. So, he decides to seek revenge on the professor by using his own knowledge of the professor's research to create chaos in the university and in the professor's personal life.
In Nutty Professor 3 fan fiction, a great plot could be that the professor accidentally creates a potion that makes inanimate objects come to life. His lab is suddenly filled with talking beakers and dancing test tubes. Meanwhile, the university is facing a financial crisis and wants to shut down his research. So, he has to figure out how to reverse the potion's effects and also save his research. He teams up with his students to put on a show using the living objects to raise money for the university and his research.
A musical - themed villain could be interesting. This villain uses 3D sound waves as weapons and creates hypnotic music to control people in the Spy Kids' world. The Spy Kids would have to break the spell of the music and find a way to silence the villain's dangerous tunes.
A voodoo priestess who is using the zombies to carry out her revenge on the islanders for past wrongs.
One popular female character could be a fictional scientist named Dr. Amelia. She's often depicted as intelligent and strong - willed. In many fanfictions, she's the one who challenges the Nutty Professor's ideas and in the end, they both learn from each other.
Ash could be paired with Professor Oak in a fan fic. Ash could return to Pallet Town and have a series of adventures with the professor, like helping him with a new research project on Mega Evolutions. They could also travel together to a new and uncharted region.
The main villain could be an escaped criminal who stumbles upon the house thinking it would be a good place to hide. But when he realizes there's a kid alone, he decides to take advantage and ransack the place. The kid has to use his wits and the resources around the house to defeat this dangerous villain.
Another angle could be a story about how Baby Buddy Love tries to make friends among the students. He might struggle at first because of his unique appearance and behavior, but eventually wins them over with his charm and sense of humor. For example, he could start a dance - off during a campus event and everyone is initially shocked but then joins in and has a great time.
One idea could be that the female character in the fanfiction is a brilliant scientist herself. She meets the Nutty Professor and they collaborate on a wild experiment that changes the world. Maybe it's an experiment about time travel, and they end up in different historical eras together, facing all kinds of challenges.
One option could be a rogue agent from within Shield who has turned against the organization. This agent could be jealous of Hawkeye's newfound status in Shield and tries to undermine him at every turn while also planning some sort of major heist or attack on Shield's assets. They might have some sort of high - tech weaponry that Hawkeye has to outwit with his arrows.
A corrupt politician could be the new villain. He uses his power and influence to cover up his illegal activities, like embezzling funds meant for the city's development. The Punisher would see through his lies and decide to take him down.