How about a crossover with the Teen Titans? Unikitty's cuteness and power could be a great contrast to the Titans' more serious superhero ways. She could help them see the lighter side of things while they teach her about teamwork in a different way.
One idea could be a Unikitty crossover with the Lego Movie characters. They could team up to save their combined Lego world from an evil mastermind. Maybe Unikitty's positive energy could inspire Emmet to be even more confident.
A crossover with My Little Pony could also be cool. Unikitty could visit Equestria and share her unique brand of fun and creativity with the ponies. They could have a big party together and learn from each other's cultures.
Well, a plot could involve Unikitty getting lost in Master Frown's territory. Master Frown at first wants to use this to his advantage, like getting ransom from her friends. But as time passes, he starts to feel a strange connection with her. He starts to protect her from other threats in his world, and in the process, they form an unlikely friendship that challenges his whole view of being evil.
The Powerpuff Girls would be great. Unikitty could join forces with them to fight crime in Townsville. Her magical powers combined with the girls' superpowers would make for an unbeatable team.
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.
One idea could be a crossover with Naruto. Kakuzu could be sent to the Naruto universe and form an unlikely alliance with a shinobi village to fight a common enemy, like the Akatsuki from his own world turned rogue in the new universe. This would create a lot of interesting character dynamics and battles.
Another option is a crossover with 'The Little Mermaid'. The characters from the descendants could meet Ariel and her friends underwater. Evie might be interested in the mermaid fashion and could design new outfits inspired by the underwater world.
Another possibility is a crossover with the world of Naruto. The characters from MHA could participate in the Chunin Exams. Bakugo might be really into showing off his skills in this new and different kind of competition.
One idea could be a Venom crossover with Spider - Man in an alternate universe where they have to team up against a common enemy like Carnage. Another could be a Venom and Deadpool crossover, with their crazy personalities clashing and then somehow working together. Maybe a Venom crossover with the X - Men, where Venom's alien nature causes some interesting reactions among the mutants.
For a Monokuma crossover fanfiction, consider a crossover with 'Final Fantasy'. Monokuma could be a summoned monster by an evil villain in the game's world, causing all sorts of problems for the heroes. He might even try to take over the crystals. A crossover with 'Persona' could also be interesting. Monokuma could enter the Metaverse and start his own 'Palace', recruiting Shadows to enforce his rules. And how about a crossover with 'One Piece'? Monokuma could be a new Warlord of the Sea, using his wacky yet dangerous devices on the Straw Hat Pirates and their allies.
One idea could be a crossover with Harry Potter. Imagine the wizards from Wizard101 going to Hogwarts and interacting with the students there. They could compare their different magic systems, like how spells are cast in Wizard101 compared to using wands in Harry Potter.
One idea could be an Ultraman crossover with Godzilla. Picture Ultraman teaming up with the giant lizard to fight a common enemy, like an alien kaiju that's too powerful for either of them alone. It would be epic to see their different powers combine, for example, Ultraman's energy beams along with Godzilla's atomic breath.