A cool crossover idea in this fanfiction could be the exploration of different dimensions. Since Decade can travel through various worlds, he could take Naruto to different dimensions within the Naruto universe that are otherwise unknown or hard to access. They could discover new types of chakra or even meet alternate versions of the ninja characters. In terms of combat, Naruto could teach Decade some ninja techniques like the Rasengan, while Decade could show Naruto how to use his Rider Cards more effectively in battle. This exchange of skills would make their battles against common enemies more exciting and unpredictable.
One interesting Kamen Rider Decade fanfiction could be about Decade traveling to different Rider worlds and teaming up with alternate versions of himself. For example, he might meet a younger version of himself in the Kuuga world and they have to work together to defeat a new, powerful enemy that is threatening all Rider worlds.
One challenge is combining the two very different universes. Naruto's world is full of ninjas, chakra, and a feudal - like society. Kamen Rider Decade's world has high - tech elements and the concept of Riders. Merging these two concepts without making it seem forced can be difficult. Another challenge is staying true to the characters. Naruto is known for his determination and his goal to become Hokage, while Decade has his own mission to travel through different Rider worlds. Keeping their personalities intact while putting them in new situations is not easy.
One idea could be exploring the backstory of Dark Decade more in - depth. Maybe there was a tragic event in his past that led him to his current path. Another could be a crossover with other Kamen Rider series, where he teams up with a Rider from a different timeline.
In a Kamen Rider Decade Crossover Fanfiction, Decade could end up in a world where the Kamen Riders are all children. He has to protect them from an evil force that wants to use their power before they fully understand it. This would involve him teaching them how to use their Rider powers in a more creative and simple way. He could also cross over with a classic monster movie world, like Godzilla's world. Decade and the Kamen Riders have to work together with the monsters to stop an even greater threat.
One interesting crossover could be the use of Naruto's ninja skills in the world of Kamen Rider Ex - Aid. For example, Naruto's shadow clone jutsu could be used to confuse the Bugsters in the Ex - Aid universe. Another crossover might involve the Riders using chakra - like energy, inspired by Naruto's world. Maybe they could even learn some basic ninja moves to enhance their combat abilities.
Well, in a Naruto and Kamen Rider Build fanfiction, we could see a situation where the Kamen Rider Build's transformation devices are scattered across the Naruto world. Naruto and his friends go on a quest to find these devices. Along the way, they encounter different challenges and enemies. As they find the parts, they start to understand how Build's powers work. They might even accidentally trigger some transformations. And once they fully assemble the device, they have to decide who will use it to fight the upcoming big threat that is attracted by the presence of Build's technology in their world.
In terms of character crossovers, Ruby could be fascinated by Gaim's transformation abilities. She might try to understand the mechanics behind it, thinking it could be a new form of power similar to her own Crescent Rose. And Gaim could learn about teamwork from RWBY's team dynamic.
Natsumi Hikari is a popular character in Kamen Rider Decade fanfiction. She provides a sort of 'normal' perspective in the otherwise extraordinary world of Riders. Writers might explore her growth from being a somewhat reluctant companion to Decade to becoming a more confident and important part of his adventures. Her relationships with other characters, especially Decade, are often a focus in fanfiction.
One of the main storylines often involves the journey of the Kamen Rider Decade through different Rider worlds. He has to face various challenges and foes specific to each world he visits.
Perhaps a story where the characters from both universes team up. Naruto could learn about Hibiki's sense of justice and Hibiki could gain some knowledge about chakra. They might combine their powers to defeat a common enemy that threatens both their worlds.