I think Orochimaru would be the most unexpected sensei. Usually, he's seen as a villain, but in a fanfiction, if he were to train Naruto, it would be extremely unexpected. He has a vast knowledge of jutsu, especially forbidden ones. He could teach Naruto some very powerful and unique abilities, but at the same time, Naruto would have to deal with Orochimaru's morally ambiguous nature.
Kurenai might be a good sensei for Naruto's different team. Her expertise in genjutsu would be valuable. She could help the team develop their skills in this area, especially if the new team members have some potential in genjutsu. Kurenai is also very perceptive, which would be great for guiding Naruto and his new teammates through difficult situations.
One possibility could be that Sakura is under Tsunade's tutelage while Naruto is trained by Jiraiya. This would lead to different styles of training. Sakura would focus more on medical ninjutsu and precise chakra control like Tsunade. Naruto, with Jiraiya, would learn more about summoning jutsu and unpredictable combat styles. Their growth paths would diverge in interesting ways, affecting how they interact with each other and their roles in the village.
One idea could be Naruto being trained by Kakashi's father, Sakumo. Since Sakumo was known for his skills, he could teach Naruto some unique jutsu and a different perspective on being a ninja. Another plot could involve Naruto being mentored by Tsunade's younger brother Nawaki. It would change Naruto's development as Nawaki might have his own special way of teaching. Maybe he'd focus more on medical ninjutsu combined with combat skills.
Naruto could use his own life story as a teaching tool. He could tell his students about how he was an outcast as a kid because of the Nine - Tails inside him, and how he overcame all the difficulties. This would inspire his students to keep going no matter what obstacles they face. He would also be very passionate about teaching them new jutsu and would probably show them some of his own unique techniques like the Rasengan.
If they had different sensei, their relationship could become more competitive. For example, if Sakura's sensei focused on making her a top - tier medical ninja quickly and Naruto's sensei was pushing him to master new powerful jutsu, they might compete to prove who is more valuable to the village.
In the fanfiction, Naruto's new sensei could be a mysterious figure who has ties to the Sage of Six Paths. This person might have been waiting for the right time to appear and train Naruto. They could possess knowledge about the origin of chakra and how to fully unlock Naruto's power. It could also be someone who was once an enemy but has now changed their ways and wants to use their skills to train Naruto for the greater good of the ninja world.
There's a chance that Naruto's new sensei could be a self - taught ninja who has developed their own unorthodox style. This person sees Naruto's ability to think outside the box and wants to refine that in him. They could introduce Naruto to a new way of looking at chakra control and combat strategies that are completely different from what he has been taught so far.
Naruto's teaching style would probably be more hands - on. Since he has always been a doer rather than just a theorist, he would likely demonstrate techniques directly to Sasuke instead of just lecturing about them. For example, if teaching a new taijutsu move, Naruto would first show Sasuke how it's done and then let Sasuke practice while he gives feedback.
Tenten would also be an interesting choice. She could focus on weapon - based combat training for Team 7. Since she has extensive knowledge of all kinds of weapons, she could introduce new and unique weapon techniques to the team.