Another possibility is that Adventure Time's Princess Bubblegum could collaborate with Sakura. Princess Bubblegum's scientific knowledge and Sakura's medical and combat skills could lead to some amazing adventures. For example, they could be working together to heal a strange illness that is affecting both the Land of Ooo and the Hidden Leaf Village.
A possible crossover in the fanfiction could involve the Digimon partners of the DigiDestined learning ninja techniques from Naruto. Picture Agumon trying to do a Rasengan - like move. This would not only be hilarious but also create a unique blend of the two universes.
One interesting crossover could be Finn and Jake from Adventure Time ending up at Hogwarts. They'd be super confused by all the magic and rules, but their unique abilities would help them get by. For example, Finn's sword -fighting skills could come in handy during a wizard duel.
One interesting crossover could be Naruto characters in the Once Upon a Time world facing magic they've never encountered before. For example, Naruto might be intrigued by the dark magic in Storybrooke. He could use his own chakra powers in unique ways to combat it or understand it better. Another idea is having characters from Once Upon a Time learn ninja techniques from Naruto. This would change the power dynamics in their own fairy - tale world and create new storylines.
One interesting plot could be that Naruto somehow ends up in the Adventure Time universe and attracts a harem of the unique characters there. Maybe he uses his ninja skills to protect them from the various threats in Ooo, like the Ice King. And as he spends more time there, different characters start to develop feelings for him.
In a Naruto - Digimon fanfiction, Sakura could team up with a healing - type Digimon. For example, a Gatomon could help her in her medical ninja skills. They could go on adventures in the Digital World, where Sakura would learn new ways of healing from the Digital environment and the Digimon's own abilities.
In such fanfiction, one interesting aspect could be Naruto's ninja skills combined with Saber's combat style. For example, Naruto's shadow clone jutsu might be used in a new way when fighting alongside Saber. His clones could create distractions while Saber attacks directly.
One interesting crossover could be a story where Naruto's world of ninjas collides with Weiss's world of Remnant. Maybe Naruto is summoned to Remnant by mistake and has to team up with Weiss to fight a common enemy. They could learn from each other's fighting styles, like Naruto teaching Weiss some of his ninja techniques and Weiss showing Naruto how to use Dust. Another idea could be a story where they both end up in a strange new dimension and have to rely on each other to find their way back home. Their different personalities, Naruto's determination and Weiss's more reserved but strong - willed nature, would create an interesting dynamic.
In a Naruto and HK 47 fanfiction, it could be about HK 47 being transported to the Naruto universe. He might initially be seen as a strange new weapon by the ninja clans. However, as the story progresses, he could start to learn about the ninja way and help Naruto and his friends in battles. He could use his precise shooting skills to assist in battles against stronger opponents.
One interesting crossover could be Naruto characters facing the chaotic and dark world of Devilman. For example, Naruto with his positive energy and never - give - up attitude might try to understand and help the tormented Devilman. Maybe Sasuke, with his thirst for power, could be intrigued by the dark powers in the Devilman universe and get into some sort of power struggle. Another aspect could be the jutsu in Naruto's world interacting with the demonic powers in Devilman's world, creating some unique and unexpected battles.
One interesting crossover could be Naruto using his shadow clone jutsu in Esdeath's world. He could send clones to gather information about the Empire while he tries to understand the political situation there. Another could be Esdeath being intrigued by Naruto's determination and chakra power, and she might try to recruit him for her own purposes.