A plot might involve Naruto being summoned accidentally to Kefla's world. Kefla is initially suspicious of Naruto but is intrigued by his strange powers. Naruto, on the other hand, is amazed by Kefla's strength. They decide to have a friendly sparring match. During the match, Naruto discovers a new form of his chakra that is influenced by Kefla's ki. This new discovery makes them both realize they can learn a great deal from each other, and they embark on a journey to explore their combined powers.
A possible plot could involve Kefla being sent to the Naruto world as part of a test by the Kais. In this world, she is intrigued by Naruto's determination. Naruto, on the other hand, is amazed by her power. They train together and learn from each other's fighting styles. This leads to a strong bond between them, and they end up protecting the Hidden Leaf Village from a powerful new threat.
One idea could be that the OC is a powerful warrior from a different dimension. They meet Kefla during a universal tournament. Their powers are so different yet complementary that they start to train together, and gradually a deep bond forms between them as they learn from each other's fighting styles.
One possible plot could be that Naruto is somehow transported to the X - Men universe. He teams up with Wolverine. Naruto's unique ninja skills, like his shadow clones, could be used in combat against the Brotherhood of Mutants. Wolverine could teach Naruto about the concept of mutants and their struggles, and Naruto could in turn show Wolverine some of his ninja wisdom.
One interesting plot could be that Naruto is somehow transported to the X - Men universe. He teams up with Wolverine. Naruto's ability to create shadow clones could be used in interesting ways during battles, like confusing the enemies. Wolverine could teach Naruto some combat skills from the X - Men's fighting style. They could go on a mission to stop a powerful mutant villain who has plans to take over the world, using Naruto's chakra powers and Wolverine's adamantium claws.
Another theme could be cultural differences. Naruto is from a ninja - based culture in the Hidden Leaf Village, while Kefla is from the Dragon Ball universe with its own set of values and ways of life. Fanfics might play with how they deal with these differences when they meet. It could lead to some humorous or thought - provoking situations. For instance, Naruto might be amazed by the technology in the Dragon Ball world, or Kefla could be intrigued by the ninja techniques.
It could be Kaguya Otsutsuki. Since she has powerful abilities and a thirst for power, she would see Kefla's power as a threat and Naruto's influence as something to be eliminated. She might try to manipulate events to turn the ninja world against Kefla and Naruto.
Well, a plot could involve a villain in the Naruto world who is creating some sort of dark energy that is affecting both dimensions. Kirby, being a hero in his own world, senses this and travels to the Naruto universe to stop it. Along the way, he teams up with Naruto. Naruto is amazed at Kirby's power to transform by swallowing enemies. Together, they face off against the villain and his minions, with Kirby using his copied ninja skills and Naruto using his jutsu.
One possible plot could be that Robocop is somehow transported to the Naruto universe. He teams up with Naruto to fight against a new threat that is using advanced technology similar to what created Robocop, but in a more malicious way. Naruto's ninja skills combined with Robocop's firepower would make for some epic battles.
One possible plot could be that Naruto is on a mission in a desert area and accidentally stumbles upon the tomb of the mummy. When the mummy awakens, Naruto initially tries to fight it, but then realizes that the mummy has some sort of connection to an ancient chakra source. They then form an uneasy alliance to explore and protect this power from falling into the wrong hands.
One possible plot could be that Naruto somehow gets transported to the Titanfall universe. He might use his ninja skills to outmaneuver the Titans at first, but then he starts to learn about the technology there and teams up with some of the Pilots. Maybe he teaches them some of his chakra - based techniques in exchange for learning how to pilot a Titan.