He could develop the ability to better withstand the different climates in One Piece. Since he's immortal, he might experiment with his body in ways others can't. Maybe he could learn to breathe underwater like a fish - man over time due to his long - lasting life.
He could develop the ability to combine the power of the Sharingan with the Nine - Tails' chakra. Maybe he could use the Sharingan to better control the Nine - Tails' power, for instance, seeing the flow of the chakra inside him more clearly. This could lead to new jutsu that are a fusion of Uchiha and Uzumaki techniques.
He could develop the ability to use the Six Paths Sage Mode more effectively. Since the Rinnegan is related to the Sage of Six Paths, it would enhance his connection to that power. He might also gain the ability to create chakra chains similar to those of the Uzumaki clan but with an added Rinnegan - powered twist.
Well, Naruto's chakra - based abilities would be quite unique in the One Piece world. His Rasengan, for instance, would be a powerful new type of attack that most characters in One Piece haven't seen. His ability to walk on walls and water using chakra would also give him an edge in many situations. He might also be able to use his chakra to sense things in a different way than the Haki users in One Piece, which could be a big advantage when exploring islands or looking for hidden treasures.
Naruto's ability to create shadow clones would be extremely useful in the One Piece world. He could send clones to gather information across different islands while he and the Straw Hats are on their main journey. His Rasengan, being a powerful concentrated attack, could be used against tough enemies like the Yonko's commanders. And his immortality means he can keep using these abilities without the fear of death, making him a very formidable ally in the One Piece universe.
Naruto's Rasengan could be seen as a super - powerful attack similar to some of the advanced Haki techniques in One Piece. His ability to create shadow clones would be a huge advantage in battles and also for things like scouting or distractions. His chakra control could potentially be related to Haki control as well. And his immortality would make him a very unique and feared presence in the One Piece world, as most characters there are not immortal.
He could develop the ability to use the Preta Path more effectively. This path allows the user to absorb chakra, and Naruto could use it to nullify enemy attacks that rely on chakra. For instance, if an enemy uses a powerful fire - style jutsu that is chakra - based, Naruto could absorb the chakra of the attack, rendering it useless.
One new ability could be enhanced physical combat skills. Tsunade's strength gives Naruto the power to deliver more powerful punches and kicks, which could be a game - changer in close - quarters battles. He might also develop the ability to use medical ninjutsu more effectively. Since Tsunade is a master of it, Naruto could learn to heal himself and others faster during battles, adding a new dimension to his fighting capabilities.
One new ability could be the power to charge his own body with kinetic energy for enhanced physical attacks. He could deliver punches or kicks that explode on contact, similar to Gambit's charged staff strikes. Another ability would be to create energy barriers by rapidly charging the air around him. This would be a great defensive move, something Naruto currently lacks in his regular skill set. He could also potentially use Gambit's power to sense the energy levels of his enemies from a distance, giving him an advantage in strategizing his attacks.
He could gain the ability to become invisible at will. The One Ring has the power of stealth in Tolkien's lore, and this could translate to Naruto being able to sneak up on his enemies undetected. He might also gain the power to influence the minds of others, which would be a huge advantage in negotiations or battles.
He could develop the ability to counter - attack more effectively. Since he can see the future, he would know exactly when and where an enemy will strike. This could lead to him developing a new fighting style that focuses on preemptive strikes and perfect defenses.