Maybe Harry Potter could be a potential crossover character. The magic in the Harry Potter universe is very different from Naruto's ninja techniques. Naruto as an immortal sage could introduce a whole new perspective on magic to the wizarding world, and they could collaborate to solve problems that neither could handle alone.
Goku from Dragon Ball could be a great crossover character. His Saiyan powers and love for combat could contrast and interact in an interesting way with Naruto's ninja skills and immortal sage abilities. They could have epic battles or team up against a common enemy.
One potential crossover character could be Harry Potter. Imagine Naruto, with his immortality, meeting Harry in the wizarding world. Naruto could teach Harry some ninja skills, and they could fight together against Voldemort. Another could be Superman. The contrast between Superman's superpowers and Naruto's ninja skills, along with Naruto's immortality, would make for an interesting story.
One potential crossover character could be Goku from Dragon Ball. Since Naruto has godlike powers in this scenario, a meeting with Goku, who also has superhuman strength and abilities, would be very interesting. They could have a friendly sparring match or team up against a common enemy.
Another potential character is Harry Potter. His wizarding skills and knowledge of magic could be a contrast to Naruto's ninja abilities. Imagine Naruto in Hogwarts, learning about magic while also showing off his ninja moves. They could also face a threat together, like a dark wizard who is trying to use both magic and chakra for evil purposes.
Maybe Naruto from Naruto could be a crossover character. His ninja skills and Ichigo's combat abilities could create some unique fight scenes. Also, their different ideologies about friendship and power could lead to some great character interactions.
Solid Snake is an obvious choice. Since they are from the same general franchise, their encounter could be filled with a lot of drama and action. They could have different views on how to handle certain situations, which would create great story tension.
In a crossover with the Attack on Titan world, characters like Eren could interact with Naruto. Eren, with his strong will to fight for freedom, could learn from Naruto's experience as a father and a hero. Levi might also be interested in Naruto's combat skills and how he trains his child in the ways of the ninja.
Definitely Hinata. She already has strong feelings for Naruto in the original Naruto series. Sakura could also be part of it as she has a long - standing relationship with Naruto. From other series, if we're doing a crossover, Erza from Fairy Tail could be an interesting addition. She's strong, independent, and would make for an interesting dynamic in a harem situation with Naruto. Also, Rukia from Bleach could be another. She has a cool and collected personality which would contrast with Naruto's more exuberant nature.
In a crossover with Fairy Tail, Lucy could be part of Naruto's harem. She is strong - willed and might be attracted to Naruto's godlike power and his kind heart. Also, from the Naruto universe, Hinata would surely be in the harem as she has always had feelings for Naruto.
Definitely Hinata. Since she has feelings for Naruto in the original series, she could be a part of the harem. Sakura might also be there as she is an important female character. From the Juubi - related side, maybe a female form of one of the tailed beasts. Also, Tenten could be included as she is a strong female ninja. And perhaps a mysterious female character who has a special connection to the Juubi's power.
Characters from 'Teenage Mutant Ninja Turtles' could be great. Imagine the Ducks and the Turtles teaming up to fight a common foe in the streets of New York. The Turtles' martial arts skills combined with the Ducks' hockey moves would make for an exciting story.