A cool Chucky crossover fanfiction could involve the 'Annabelle' universe. Since both are about evil dolls, they could either team up, which would be terrifying, or be in a battle for the most feared doll. Also, a crossover with 'Scooby - Doo' would be fun. The gang could be investigating a series of strange happenings that turn out to be caused by Chucky.
For a Chucky crossover fanfiction, you could consider a crossover with the 'Saw' franchise. Chucky might find himself in one of Jigsaw's traps and have to figure out a way to escape while also causing his own brand of mayhem. Or a crossover with the 'Goosebumps' series, where he meets Slappy the Dummy and they have a rivalry over who is the better evil doll.
A plot idea could be that Chucky gets cursed in a way that he is forced to protect Andy. So, he has to follow Andy around and keep him safe from other threats in the horror - filled world they inhabit. This would lead to a lot of comical and also tense situations as Chucky is not used to being a protector. And they could gradually develop an understanding of each other's perspectives during this time.
One idea could be that Chucky and Buddi form an unlikely alliance to take on a common enemy in the toy world. Maybe a new, more evil toy is threatening their existence.
A really interesting plot could be that Chucky and Tiffany discover a way to reverse their doll - turned - human situation. But as they try to do so, they face various obstacles, like a powerful enemy who wants to keep them as humans for their own malicious purposes. They have to fight this enemy while also dealing with their own internal conflicts about whether they really want to go back to being dolls.
One idea could be that the reader is a detective trying to solve the mystery of Chucky's murders and ends up in a strange psychological battle with him. Another could be that the reader is a dollmaker who discovers Chucky's true nature and has to decide whether to help him or stop him. Or perhaps the reader is a psychic who can communicate with Chucky on a spiritual level and tries to exorcise his evil.
One idea could be that Andy, now grown up, has to face Chucky again when Chucky resurfaces in a new, more devious form. Maybe Chucky is using modern technology to his advantage, like hacking into security systems to get to Andy.
One interesting idea could be a crossover with "Moana". Elsa's ice powers and Moana's connection to the ocean could create a really cool dynamic. Maybe Elsa accidentally freezes part of Moana's ocean and they have to work together to fix it. Another could be with "Tangled". Rapunzel's long hair and her adventurous spirit combined with Elsa and Anna's journey in Frozen 2 would be exciting. Rapunzel could use her hair to help them climb mountains or cross chasms. A third idea is a crossover with "Beauty and the Beast". Belle's love for books and knowledge could help Elsa understand more about her powers and the history of magic in the Frozen world.
A Thundercats and Star Wars crossover fanfiction would be really cool. The Thundercats could be in the Star Wars universe, and their unique powers and weapons could be a great addition. Maybe the Thundercats could help the Jedi or the Rebels in their fight against the Sith or the Empire. For instance, Cheetara's speed could be useful in battles, and Tygra's illusions could be used to deceive the enemy.
A Digimon and Sailor Moon crossover is an interesting concept. The Digimon could help the Sailor Scouts in their battles against the Dark Kingdom. The magical powers of the Sailor Scouts combined with the digital powers of the Digimon would create a really unique and exciting story. And a Digimon and Avatar: The Last Airbender crossover. The Digimon could be part of the different nations, and they could use their abilities to help Aang and his friends in their quest to restore balance.
First, decide which other franchise or story you want to cross Chucky over with. Then, think about how the two worlds would collide. For example, if it's a crossover with 'The Simpsons', how would Chucky end up in Springfield? Maybe he stows away in a shipment to the local toy store. After that, start planning the plot. Will Chucky be the main villain or will there be a new threat that he and the other characters have to face together?
One idea could be an Atreus crossover with the world of Harry Potter. Atreus could be a new student at Hogwarts, bringing his own unique skills and knowledge from his Norse mythology background. He might struggle to adapt to the magic of the wizarding world while also showing off his own combat and survival abilities.