One idea could be Hiruzen teaching Naruto some of the most secret and powerful jutsu in the village. For example, a special fire - style jutsu that was once used by the First Hokage. This would give Naruto an edge and also show the bond between him and Hiruzen. Another plot could be Hiruzen training Naruto in the art of political leadership. Since Naruto is destined to be a great leader, Hiruzen could impart his wisdom on how to handle different clans and political situations within the village.
In the fanfiction, Hiruzen could train Naruto in the ways of stealth. Naruto is often very straightforward in his approach, but Hiruzen could teach him how to be more sneaky. They could have a mission where Naruto has to infiltrate an enemy base, and Hiruzen guides him through every step. This would be a new aspect of Naruto's training that we don't see much in the original series.
One idea could be that Jiraiya focuses on Naruto's rasengan training in a more extreme way. He takes Naruto to a secluded place full of natural challenges like strong water currents or rocky terrains. There, Naruto has to constantly adapt and use his rasengan in different situations to overcome obstacles. Another plot could involve Jiraiya teaching Naruto some secret clan jutsus that he discovered during his travels, which could give Naruto an edge in future battles. And also, Jiraiya could train Naruto in stealth and espionage skills, which are essential for a shinobi but Naruto hasn't had much focus on before.
One plot idea could be that Sakura, through some time - travel jutsu, ends up in Hiruzen's era. She uses her medical ninjutsu knowledge to help in a major epidemic that is plaguing the village at that time. Hiruzen, impressed by her skills, takes her under his wing as a sort of special advisor for medical matters in the village.
One idea could be that Hashirama teaches Naruto some long - lost wood - style jutsu. Maybe Hashirama shows Naruto how to use wood - style for more than just combat, like for building and healing in the village.
One possible plot idea could be that Madara sees Sakura's potential in medical ninjutsu and trains her to combine it with combat in unique ways. For example, she could learn to use her medical chakra to enhance her physical attacks or to disrupt an opponent's chakra system more effectively during battle.
One idea could be that Genma is tasked with training Sakura in a special form of combat. He takes her to a secluded place and teaches her unique jutsu. Along the way, they face various challenges that test not only Sakura's physical skills but also her mental strength.
One interesting story could be about Hiruzen mentoring Naruto in some unique jutsu that was long forgotten. This would show a different side of their relationship, focusing on the transfer of knowledge from the old to the new generation.
One plot idea could be that Sakura, in her pursuit of medical ninjutsu knowledge, discovers some ancient scrolls that were once in Hiruzen's possession. She then tries to seek out the secrets within them with the help of Hiruzen's spirit or memories that somehow still linger. This could lead to her developing a new form of medical ninjutsu that combines old and new knowledge.
One interesting plot line could be Ibiki teaching Naruto advanced interrogation techniques. Naruto might initially struggle but then start to pick up on Ibiki's skills and use them in unique ways during battles or when dealing with enemies. For example, he could use the psychological aspects of interrogation to outwit opponents on the battlefield.
Naruto would become more well - rounded. With Hiruzen's training, he'd gain more discipline. In the original, Naruto was a bit of a wild card. But under Hiruzen, he'd learn to control his impulses better. For example, in battles, he'd think more strategically instead of just charging in.
One interesting 'naruto trains fanfiction' could be about Naruto using his shadow clones to help build a new railway system in the Hidden Leaf Village. This would show his determination and unique use of his jutsu in a non - combat situation.