One idea could be that Naruto, as a sensei, takes on a student who has a similar past to Zabuza. He uses his knowledge of Zabuza's story to teach the student about redemption. For example, Naruto could tell the student how Zabuza was once a feared assassin but had a side that was capable of love and loyalty, as seen with Haku.
A different plot might be that Naruto, in his role as a sensei, is faced with a new threat that has some connection to Zabuza's old techniques or his past. He has to study Zabuza's fighting style in order to come up with a counter - strategy. His students then learn about Zabuza indirectly through Naruto's teachings and research.
One plot idea could be that Naruto and Female Zabuza team up on a special mission in a hidden land. They have to face a powerful enemy who has the ability to manipulate time. Along the way, they learn about each other's pasts and Naruto helps Female Zabuza come to terms with her own troubled history.
A great plot could be Itachi teaching Naruto how to control the Nine - Tails' chakra in a completely different way than Jiraiya did. Since Itachi has such a deep understanding of chakra and its nature, he could offer unique insights. Also, there could be a story where Itachi and Naruto are forced to team up against a common enemy that is using an ancient and powerful jutsu. In the process, Itachi passes on some of his Uchiha clan's wisdom to Naruto. And perhaps, Itachi could help Naruto deal with the loneliness that often comes with being a jinchuriki, as Itachi has also felt isolated in his own way.
A great plot could be that Naruto, as sensei, takes Team 7 on a diplomatic mission to another hidden village. Along the way, they face various challenges that test their teamwork and understanding of different cultures. This could lead to some interesting character development for the members of Team 7. Another idea is that Naruto discovers a prophecy related to one of the Team 7 students. He then has to train and guide this student to fulfill their potential and avoid a dark fate predicted in the prophecy. And there could be a story where a powerful enemy targets Team 7 specifically because of Naruto's influence on them, and Naruto has to find a way to protect his students while also uncovering the enemy's motives.
One idea could be Naruto teaching Anko a new jutsu. He could use his unique experiences and skills to help her expand her abilities. Another plot could involve them going on a mission together where Naruto has to rely on Anko's knowledge of certain areas or enemies. For example, Anko might be familiar with a particular type of snake - related enemy, and Naruto has to trust her expertise.
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.
Perhaps Naruto, as Minato's sensei, could focus on teaching Minato about the importance of bonds. Minato was always a bit of a loner in terms of his natural talent. Naruto could show him how his friends and comrades are his greatest strength. This could lead to Minato making different decisions in his life, such as being more open with his teammates and relying on them more in battles.
Zabuza could be portrayed as more of a mentor figure. Instead of just being a ruthless assassin, he could be shown guiding Naruto in some aspects of combat or strategy. Maybe he survived his encounter with Kakashi and had a change of heart, and now he imparts his knowledge to Naruto who is now a sensei himself.
Another idea is that Sakura, feeling she still has much to learn from Kakashi, asks him for one - on - one training. As they train, Kakashi reveals some of his own past traumas which Sakura helps him deal with in her own way, while also growing stronger in her ninja skills. This could also lead to a deeper bond between them as teacher and student.
You could also create a 'naruto sensei fanfic' where Naruto takes on a special student from a foreign land. This student has different chakra abilities that Naruto has never seen before. Naruto has to adapt his teaching methods to help this student master their powers while also learning from the student's unique skills.
One idea could be a crossover where Naruto characters end up in the Mahou Sensei Negima world and have to adapt to the magic there. Maybe Naruto tries to learn magic instead of chakra techniques.