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.
Think about the themes you want to explore. In an Ultraman and Sailor Moon crossover, you might explore themes of heroism and friendship. You can start by writing a scene that shows the contrast between Ultraman's more serious, alien - fighting nature and Sailor Moon's more magical, girl - power approach. This contrast can drive the story forward and create interesting interactions between the characters.
Some niche forums and communities dedicated to Ultraman or Digimon might also have fanfiction crossovers shared by their members. For example, there could be a specific Ultraman fan forum where someone has written and shared a crossover with Digimon. You'd have to do some digging around in these smaller communities.
A cool plot could be Geed crossing over with a human superhero from another franchise. For example, he meets a spandex - clad hero who has no experience with giant monsters. Geed has to teach this hero how to fight in a world where the threats are so much bigger, and together they face a villain who has the ability to control both technology and kaiju.
Ultraman Zero would be a great addition. He's a well - known and powerful Ultraman. His relationship with Geed, as his mentor in a way, could be further explored in a crossover. They could have some really intense battles side by side.
One idea could be Ultraman Nexus crossing over with another Ultraman, like Ultraman Tiga. They could team up to fight a powerful new enemy that is a combination of their previous foes. This would bring together different fighting styles and powers.
Definitely include the main characters from Ultraman Nexus like the various forms of Nexus. Also, characters like Ultraman Noa could be interesting to bring in for added power and mystery.
Definitely include Ultraman Belial. Their rivalry can add a lot of tension and action to the fanfiction. When they cross paths in a new crossover setting, it could lead to some epic battles.
Another plot could involve Ultraman Zero crossing over to a post - apocalyptic Earth. He finds a group of survivors who are fighting against mutated monsters. Zero has to use his powers not only to defeat the monsters but also to help the survivors rebuild their society, teaching them about hope and perseverance.
Definitely Ultraman Zero. He's a very popular Ultraman and his skills and personality would make for an interesting combination with Ultraman Orb. They could have some friendly rivalries while fighting side by side against a common foe.