There might be a fanfiction where they are all involved in a medical emergency. Since Tsunade is a great medical ninja and Sakura is her apprentice, and Naruto is always in the thick of things. They have to work together to save a village from a mysterious illness. It would be full of drama and moments of them relying on each other's skills.
The plot could involve a mystery in the village. Strange things start happening, and Naruto, Sakura, and Tsunade have to work together to solve it. Along the way, they face various challenges, and their individual skills and teamwork are put to the test. They also learn more about each other's pasts and how it relates to the current mystery.
I think all three are great in their own ways. Naruto is the heart of the story, his optimism and determination are infectious. Sakura has the potential to be a complex and strong female character. She can have her own character arc that is independent yet related to Naruto and Tsunade. Tsunade, with her long history and powerful abilities, can be a source of both conflict and resolution in the fanfictions. For example, her past experiences can create interesting plot twists when combined with the current situations of Sakura and Naruto.
For Naruto, he could develop by learning more about leadership from Tsunade. He already has his own unique style, but Tsunade's wisdom in leading the village could give him new insights. Sakura could develop her medical ninjutsu further under Tsunade's guidance and also become more confident in her combat abilities. Tsunade herself could develop by seeing the new generation, Naruto and Sakura, grow and be inspired to take on new challenges for the village.
One common plot is a training arc where Tsunade trains Sakura further in medical ninjutsu and combat skills, with Naruto sometimes getting involved as a sparring partner or for moral support.
In some fanfictions, a time - travel plot could be involved. For example, Sakura and Tsunade are sent back in time and have to deal with the early days of the Hidden Leaf Village. They meet a younger version of Naruto's parents and play important roles in shaping the future, which also has a significant impact on Naruto when they return to their own time.
They could start training together more often. Since Tsunade is a great medical ninja and has a lot of combat experience, she could teach Sakura some advanced medical and combat techniques. This shared learning experience would strengthen their bond.
A cool fanfiction idea could be that Tsunade sends Naruto and Sakura on a diplomatic mission to another village. Along the way, they face various challenges that test their loyalty to the Hidden Leaf and to each other. Through these trials, they learn more about themselves and their place in the ninja world.
A Tsunade - Sakura kiss in fanfiction could be a sign of a deep bond. It might represent a mentor - mentee relationship evolving into something more like a sisterly or mother - daughter - like affection. Maybe in the fanfic, Tsunade sees Sakura's growth and is proud, and the kiss is a way to show that.
A possible plotline could be a training arc. Tsunade could be training both Naruto and Sakura in a new and advanced form of combat or medical ninjutsu. This would involve a lot of character development as they struggle to master the new skills. For example, Naruto might have trouble with the precision required in a medical - related technique while Sakura helps him out, and Tsunade observes and gives tough love guidance.