One idea could be a crossover with the 'Dragon Ball' universe. Naruto's descendants could team up with Goku's family to fight a common enemy. Another could be a crossover with 'One Piece', where they sail the Grand Line together in search of a powerful treasure that could change both their worlds. Or perhaps a crossover with 'Bleach', and they battle Hollows and Soul Reapers together in the afterlife.
One idea could be a character from Naruto ending up in the Descendants' world. For example, Naruto himself could be transported there. He might use his ninja skills to deal with the challenges in the Descendants' world, like facing off against the villains in a very different way compared to the Descendants' characters. Maybe he'd use his shadow clone jutsu to confuse the bad guys or his Rasengan to take on powerful foes.
One idea could be a story where the characters from 'Descendants' end up in the 'Twilight' world. For example, Mal could meet Bella and they could form an unlikely friendship. Mal might be intrigued by Bella's relationship with Edward and the whole vampire - human dynamic in the 'Twilight' world.
One idea could be that a character from 'Once Upon a Time' (OUAT) accidentally travels to the world of 'Descendants'. For example, Emma Swan could end up there and have to deal with the different rules and characters. Maybe she tries to help some of the 'villain kids' in 'Descendants' to see that they don't have to follow in their parents' footsteps, just like she often helped people in OUAT find their true selves.
One idea could be that the characters from Descendants end up in the world of Jessie by some magical mishap. Mal could use her magic to help Jessie deal with some of the difficult kids she babysits, like when they get into trouble at school. Another plot could be that the kids from Jessie visit the Isle of the Lost out of curiosity and try to bring some positive change there. Maybe they start a music club or something similar to engage the villain kids in a more positive activity.
One idea could be that the demigods from Percy Jackson's world accidentally end up in the Descendants' universe. They could team up with the VKs (Villain Kids) to face a common threat that is related to both Greek mythology and the magic in the Descendants world. For example, an ancient Greek monster that has been awakened by the dark magic in the Isle of the Lost.
One idea could be a Naruto and One Piece crossover. Naruto and Luffy could meet and have to team up to defeat a common enemy that threatens both their worlds. Maybe a powerful dark force that can manipulate the sea and the land.
In a Naruto Marvel crossover fanfiction, it could be interesting if the X - Men visited the Hidden Leaf Village. Naruto might be fascinated by the mutants' powers and their struggle for acceptance. He could compare it to the discrimination some ninja faced in his own world. The X - Men could also learn from the ninja's stealth and combat techniques. Wolverine, for instance, might spar with Rock Lee and learn some new hand - to - hand combat moves, while Cyclops could study how the ninja use their eyes in combat, like the Sharingan.
One idea could be that Naruto characters end up in the world of Danmachi. For example, Naruto himself could be mistaken for a new type of adventurer with his unique skills like shadow clones. His clones could be used to explore dungeons more efficiently, confusing the locals. Another idea is that Sasuke, with his Sharingan, might be able to quickly analyze the monsters in the Danmachi dungeons, giving him an edge in combat. And Sakura could use her medical ninjutsu to heal the injured adventurers in the world of Danmachi, which would make her a highly sought - after healer.
Maybe the Akatsuki members could be a villainous wrestling gang. They could use their unique abilities, like Sasori's puppet techniques as part of their wrestling moves. Picture Sasori controlling puppets to attack his opponents in the wrestling ring while the referee is trying to figure out if it's legal or not.
In a Pokemon and Naruto crossover fanfiction, there could be a tournament where both Pokemon trainers and ninjas participate. The ninjas would use their jutsu and the trainers their Pokemon. It would be interesting to see how Naruto's Rasengan would compare to a powerful Pokemon move like Hyper Beam. And perhaps some Pokemon could learn to use jutsu from the ninjas they befriend, creating a whole new dynamic in the story.