Sakura could also be present. She might be observing the training and learning some things herself, or she could be helping Kakashi in some way, like providing medical support during intense training exercises.
One possible plotline could be Kakashi teaching Naruto some super - advanced jutsu that Naruto then uses to surprise his friends in a sparring match. For example, Kakashi might teach Naruto a special lightning - style jutsu that Naruto masters and combines with his Rasengan.
Well, one possible plot could be that Naruto, having experienced so much growth himself, decides to pass on his unique ninja skills and values to a young Kakashi. He might teach Kakashi some of his signature jutsus like the Rasengan, but also lessons about friendship and never giving up. Naruto could also share his own experiences of dealing with loss and loneliness, which would be really interesting considering Kakashi's own past traumas.
He might learn some advanced chakra control techniques. For example, better management of his Nine - Tails chakra. Kakashi, being a skilled ninja, could teach Naruto how to blend his own chakra with the Nine - Tails' more effectively, which would enhance his combat abilities.
Kakashi's training style, which is often strict and methodical, would likely make Naruto more disciplined. Naruto is usually a bit of a wild card, but under Kakashi's tutelage, he would have to follow a set routine and be more precise in his actions.
Their relationship would likely start off a bit rocky. Kakashi is a proud and skilled ninja even as a young boy, and Naruto coming in to train him might be seen as an intrusion at first. But as Naruto shows his genuine care and his own amazing skills, Kakashi would start to respect him. Eventually, they'd become like brothers, with Kakashi looking up to Naruto in some ways.
Well, there could be a plotline where Naruto, under Kakashi's training, discovers a new power within himself that was previously untapped. This new power could draw the attention of powerful villains outside the village. Meanwhile, the relationship between Naruto and Sasuke would also change. Since Naruto is getting better training, Sasuke might feel jealous or motivated to find a different kind of training. This could lead to a more complex dynamic between them, different from the original story.
One of the main challenges is time management. The Chunin Exams are approaching fast, and Naruto has a lot to learn. He has to quickly grasp complex ninja techniques that Kakashi is teaching. Another biggie is dealing with his own impatience. Naruto is eager to prove himself and might rush through the training, not fully absorbing the lessons.
Kakashi's training style is intense and methodical. This helps Naruto focus more. For example, if Kakashi makes Naruto repeat a jutsu until he gets it right, it builds Naruto's perseverance.
I'm not sure specifically which 'kakashi trains sakura fanfiction' is the best. But if you search on popular fanfic sites, you might find some. It could be interesting to see how different authors imagine Kakashi passing on his knowledge and skills to Sakura. Maybe in some, he's strict and in others, more lenient.