It could be an epic adventure. Imagine Godzilla in the Star Wars universe, perhaps on a planet like Hoth. The Empire could try to capture it for its power, and the rebels might see it as a force of nature that could help them. Godzilla's size and strength would be a huge asset or a terrifying threat depending on which side it's on.
It could be a really wild and imaginative mix. Maybe an Emperor - like figure in the Harry Potter universe who has the dark powers similar to those in Star Wars. For example, using the Force - like magic to control others, and Hogwarts could be like a battleground between the forces of good and this new 'emperor' power.
You need to consider the characters. Which Star Wars characters will interact with Godzilla? Luke Skywalker might have an interesting reaction. You also have to decide on Godzilla's role. Is he a hero, a villain, or something in between? And don't forget about the action scenes. How will Godzilla's abilities work against Star Wars technology and the Force?
One idea could be to have Sekirei characters possess unique Force abilities. For example, a Sekirei might be able to use the Force to enhance their physical combat skills in a way similar to their natural powers in the Sekirei universe. They could be part of a new Jedi order or Sith group in the Star Wars galaxy.
One idea could be a story where the XCOM 2 soldiers are transported to the Star Wars universe. They could use their advanced tactics and technology to fight alongside the Rebel Alliance against the Empire. For example, their psionic abilities could be seen as a new form of the Force by some in the Star Wars world.
Perhaps a fanfiction where some of the Naruto characters are actually clones themselves, like in The Clone Wars. Naruto could be a special clone created with a combination of chakra and the Force. His purpose could be to bring peace between the two universes. Hinata could be a healer in this new world, using her gentle nature and Byakugan to sense injuries and use the Force to heal them. This would mix the two universes in a unique way and create a lot of new storylines.
Well, in such a fanfiction, there could be crossovers of characters. Naruto might meet Kenshiro, the main character of Fist of the North Star. They could exchange combat skills or fight together against common enemies. The story could also involve a new kind of power system that combines chakra and the 'Hokuto Shinken' martial art. It would be a whole new world of adventure and battles, with Naruto's friends and the world of ninjas being introduced to the post - apocalyptic and violent world of Fist of the North Star.
Well, it could involve the characters from Harry Potter somehow getting on board a Star Destroyer. Imagine Harry, Ron, and Hermione exploring the massive ship, trying to understand its technology. They might use magic to disguise themselves among the Imperial crew. And there could be a plot where they have to stop the Star Destroyer from attacking Hogwarts, perhaps by finding a way to disable its weapon systems using a combination of magic and their wits.
One idea could be that Percy and his friends find themselves in the Star Wars universe. Maybe they land on a planet that's rich in water, like Naboo. Percy could use his water - controlling abilities to help the locals against some kind of threat, like the Trade Federation. Meanwhile, the Jedi could sense the different kind of power Percy has and be both intrigued and cautious.
Another possibility is that Godzilla somehow ends up in the Naruto world. The shinobi might initially see it as a great threat, but Naruto could try to communicate with it using his ability to sense emotions. Maybe Godzilla is there because it's being chased by an even greater enemy from its own world, and Naruto and his friends decide to help it.
One idea could be a crossover where the Rebels' technology somehow gets mixed with Halo's. For example, the Rebels might discover a Halo ring and try to figure out its purpose while also dealing with Covenant forces. Maybe Ezra could use his Force abilities in new and unexpected ways against the alien threats.