Naruto would probably get Madara's Sharingan abilities. This could give him enhanced perception and the ability to copy jutsu more easily, like a supercharged version of his own ability. He might also gain access to Madara's Susanoo, which would be a huge boost to his combat capabilities.
Well, in such a fanfiction, Madara's training might enhance Naruto's physical strength. He could teach Naruto some advanced Uchiha techniques which Naruto can combine with his own Uzumaki powers. For example, Naruto might learn better chakra control from Madara, enabling him to use his Rasengan more effectively and with less chakra waste.
For Naruto, being trained by Madara could mean he learns how to counter Uchiha - specific techniques more effectively. His physical strength might also increase due to the intense training. Sasuke would be able to better harness his hatred and turn it into a more focused power source. Madara's teachings could expose them to ancient jutsu and knowledge that would give them an edge over their enemies. Their teamwork might also be affected, as they would both be influenced by Madara's way of thinking.
His combat abilities would become more diverse. Madara could teach him new forms of taijutsu and ninjutsu. For example, Naruto might learn some of Madara's signature space - time ninjutsu, which would give him an edge in battles. His chakra control would also improve as Madara is very proficient in chakra manipulation.
Their combined abilities would likely make them the most powerful entity in the ninja world. For example, Naruto's ability to sense negative emotions and Madara's combat experience could lead to a new form of justice. They could easily defeat any rogue ninja or group that threatens the peace.
Madara's Sharingan would be a very unique ability in the Harry Potter world. It could be used for things like detecting lies, seeing through invisibility spells that are not as advanced as the Sharingan's capabilities, and predicting an opponent's moves in duels. His ability to use fire - based jutsu could be seen as a form of very powerful and different magic. Also, his physical combat skills would make him a formidable opponent in a world where most rely on wands for combat.
Naruto could potentially use a new form of the Nine - Tails Chakra Mode. Maybe he combines it with his Sage Mode in a more seamless way than ever before. This would give him enhanced strength, speed, and the ability to sense danger more acutely.
First of all, having Madara's eyes would likely give Naruto access to some of the unique abilities associated with the Uchiha bloodline. For instance, he could potentially unlock the Mangekyou Sharingan's special techniques. This could change his combat style significantly. He might be able to use Amaterasu, the black flames, which would add a whole new dimension to his offensive capabilities. Also, the Sharingan could help him better understand and counter genjutsu, which is something that he wasn't as proficient in before. This would make him a more well - rounded shinobi in the fanfiction world.
Naruto would likely have enhanced Sharingan abilities. He could potentially skip some of the normal progression steps of the Sharingan and quickly reach advanced levels like the Mangekyo Sharingan. His physical abilities might also be enhanced due to the Uchiha bloodline. Maybe he would have better reflexes and speed. Also, he could inherit some of Madara's unique jutsu or at least have an easier time learning similar ones.
Naruto would likely gain the ability to use all six paths techniques. The Rinnegan allows the user to manipulate gravity, as seen when Madara used it. Naruto could use this to enhance his combat skills, for example, pulling enemies towards him or pushing them away forcefully. He could also use the Preta Path to absorb chakra, which would be a great addition to his already large chakra reserves.