One idea could be that Naruto is somehow transported to the world of the Lich King. He might use his ninja skills, like shadow clones, to fight against the undead minions of the Lich King. His chakra could be seen as a strange and new form of energy in that world.
Perhaps a wizard from Hogwarts gets transported to the world of the Lich King. He has to use his magic in new and unexpected ways to survive among the undead hordes. For example, he could use transfiguration spells to change the appearance of the undead, causing confusion among them.
One idea could be that Naruto is transported to the Godzilla universe. He could use his ninja skills to try and communicate with Godzilla or other kaiju. Maybe he'd attempt to use his shadow clone jutsu to confuse the monsters during a battle.
One idea could be that Naruto characters are summoned as Servants in FGO. For example, Naruto himself could be a Berserker with his never - give - up attitude and powerful chakra being translated into high - level stats. Sasuke could be an Assassin, using his Sharingan to detect and strike enemies stealthily.
A more serious fanfic could be set in a post - apocalyptic world that was destroyed by a combined force of villains from both Naruto and Bleach universes. Naruto and Ichigo are the last hopes. They meet and initially clash due to their different ways of fighting and beliefs. But they gradually learn from each other and combine their powers in a unique way to take on the remaining villains and try to restore their worlds.
One idea could be that Venom somehow ends up in the Naruto universe. Maybe a strange rift in dimensions brings Venom to Konoha. He could initially be seen as a threat, but Naruto, with his ability to see the good in people (or in this case, symbiotes), tries to befriend Venom. This could lead to some really interesting battles and storylines, like Venom helping Naruto against powerful enemies using his unique powers.
A fanfic could be written where Alita is reincarnated in the Naruto universe as a ninja. She retains her combat skills but has to learn how to use chakra. Naruto becomes her friend and helps her adapt. They go on adventures together, facing off against powerful enemies. Alita's unique fighting style would make her stand out among the ninjas, and together they could become a formidable team.
One idea could be that Deadpool somehow gets transported to the Naruto universe. He'd be really confused at first but then start causing all kinds of chaos with his unorthodox fighting style and fourth - wall - breaking humor. Maybe he'd try to team up with Naruto, thinking he could use some of Naruto's cool jutsu in his own battles back home.
Well, Naruto is a very empathetic character. He might try to find the good in the Lich King, or at least the reason behind his actions. He could offer the Lich King a chance at redemption, using his own story of how he overcame his inner darkness. On the other hand, the Lich King might see Naruto as a powerful new minion or a threat to his rule.
One idea could be a story where Naruto is somehow transported to the DxD universe and meets Ophis. He could form an alliance with her, perhaps because they both have a sense of being outsiders in the new world. Naruto's unique skills and his never - give - up attitude could influence the events in the DxD world in interesting ways.
One idea could be to have Naruto characters transported to the world of Shadow of Mordor. For example, Naruto himself could use his shadow clones in the same way the main character in Shadow of Mordor uses the wraith abilities. His clones could be used for stealth and surprise attacks, just like the wraith's powers are used in the game. It would be interesting to see how Naruto's positive and determined attitude would contrast with the dark and gritty world of Shadow of Mordor.