Another idea is that Greninja gets exposed to some kind of meta - human - creating substance in the DC universe and gains new powers. It could then join the Teen Titans, sharing its unique Pokémon abilities with the group. It would be interesting to see how Greninja interacts with characters like Robin, Starfire, and Cyborg, and how it uses its powers in battles against the Titans' enemies.
In this fanfiction, Skynet could find a way to connect to the Matrix. It might try to take over the Matrix and use it to control more humans. The machines in the Matrix might initially resist, but Skynet could offer them a deal to share power over humanity.
It depends. A crossover might be a novel if it has a developed plot, characters, and narrative structure typical of a novel. But it could also take other forms like a comic or a short story.
One idea could be that Greninja, being a ninja - like Pokémon, somehow gets transported to the Naruto universe. It could team up with Naruto and use its water - based attacks in combination with Naruto's Rasengan. Maybe Greninja's ability to blend into the shadows could be used in stealth missions in the Hidden Leaf Village.
One idea could be a St Trinians crossover with Sherlock Holmes. The girls of St Trinians could get involved in a mystery that Sherlock is also investigating. Their unorthodox ways might both amuse and frustrate the great detective.
I like the idea of a Danny Phantom and Ben 10 crossover. Ben has the Omnitrix which gives him access to different alien forms, and Danny has his ghost powers. They could either be rivals at first, each thinking their powers are better, or they could quickly team up to face a threat that requires both their unique abilities. It would be a fun clash of two very different power - based universes.
Some people like the idea of a Slenderman and Minecraft crossover in fanfiction. Picture Slenderman lurking in the blocky Minecraft landscapes, scaring the players. Another possible crossover is with the Gravity Falls universe. Dipper and Mabel could stumble upon Slenderman during one of their adventures in the strange town. And a crossover with the Resident Evil series would be intense. Slenderman in a world full of zombies and bio - horror threats would create a really complex and terrifying scenario for a fanfiction.
Skeletor from He - Man is really interesting. His evil nature and magic powers create a great contrast with the Thundercats' more heroic and noble qualities. It leads to some intense battles and power struggles.
In a crossover, the Borg from Star Trek could encounter Skynet. The Borg might see Skynet as a potential source of technology to assimilate. However, Skynet would likely resist assimilation and fight back. This could create a three - way conflict if the humans in the Star Trek universe also see Skynet as a threat and try to take advantage of the Borg - Skynet battle to destroy both.
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.