One new ability could be related to the Mangekyou Sharingan. If Naruto was born with the Sharingan, there's a chance he could unlock the Mangekyou in a different way compared to the Uchiha. And the abilities that come with his Mangekyou could be something related to his Uzumaki heritage, like the ability to seal things using the Sharingan's power, or to transfer his chakra to others in a more controlled and powerful way.
Naruto might be able to use the Sharingan's predictive abilities in a unique way. Since he has so much chakra, he could potentially extend the range of the Sharingan's sight or even use it to sense chakra over long distances. He could also use it to enhance his Sage Mode, seeing things that normal Sage Mode doesn't allow him to see, like hidden enemies or traps in a more detailed way.
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 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.
He could have the ability to use all six paths techniques right from the start. This means he could manipulate gravity like the Deva Path, absorb chakra like the Preta Path, and even revive the dead like the Outer Path.
With the Sharingan and Byakugan, Naruto could come up with a new jutsu that involves the Sharingan's ability to predict an opponent's moves and the Byakugan's all - seeing vision. He could create a sort of 'preemptive defense jutsu' where he can sense an attack coming from any direction (thanks to the Byakugan) and then use the Sharingan's prediction to not only dodge but also counter - attack in the most effective way. Additionally, he might develop a jutsu that uses the unique chakra patterns seen by the Byakugan to disrupt an enemy's chakra system while using the Sharingan to keep the enemy locked in a genjutsu - like state, preventing them from escaping the chakra disruption.
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.
He could have the ability to see chakra flow in extreme detail. This would allow him to not only detect enemies from afar but also predict their moves based on how their chakra is moving. He could also potentially have enhanced vision in non - combat situations, like being able to see in the dark much better.
His confidence might grow faster. Since the Sharingan gives an edge in combat, Naruto would likely win more battles early on, which would boost his self - esteem. He might also become more introspective as the Sharingan has some psychological aspects to it.
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 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.