Kaguya might start with chakra control training. Since she has such a deep understanding of chakra, she could teach Naruto how to refine his chakra even more. For example, she could show him how to make his chakra flow in a more stable and efficient way. She may also use her knowledge of space - time ninjutsu to train Naruto in that area. Maybe she'd create special training grounds using her space - time abilities to test Naruto's reaction and adaptability.
Kaguya would probably start with the basics but in a more advanced way. She might teach Naruto about the true nature of chakra, not just how to use it for jutsu but also how it relates to the world around them. In terms of more hands - on training, she could use her powerful attacks to force Naruto to learn how to dodge and counter. She'd also likely train him in stealth and perception, skills that are important in any battle. And she might introduce Naruto to some of the ancient Otsutsuki techniques that are far more powerful than the normal ninja techniques.
They could do endurance training, like running long distances while also practicing weapon - handling for Tenten and chakra control for Naruto.
In the fanfiction, Jiraiya's training methods for Naruto are comprehensive. Firstly, there's the physical aspect. Jiraiya could be making Naruto do things like carrying heavy rocks for long distances to build up his endurance. For ninjutsu, he'd be teaching Naruto not just new techniques but also how to innovate and combine existing ones. He might also take Naruto on dangerous missions where Naruto has to learn on the fly. Jiraiya would also focus on Naruto's mental strength, teaching him how to stay calm under pressure and not let emotions cloud his judgment during battles.
Minato may use sparring sessions with clones. He could create multiple clones of himself and have Naruto fight against them all at once. This would improve Naruto's multitasking ability and his reaction time, which are essential skills for the exams. Also, Minato could give Naruto tips during the sparring to help him improve his techniques.
One unique method could be poison resistance training. Anko is known for her use of poison, so she might expose Naruto to small amounts of non - lethal poison to build up his resistance. This would give him an edge in case he faces opponents who use poison in the Chunin Exams.
He might start with basic physical training. You know, like running up mountains or doing a lot of push - ups to build strength. Also, chakra control exercises would be key. He could teach his younger self to focus chakra on different parts of the body for more effective jutsu use.
Minato would likely focus on Naruto's natural strengths. Since Naruto has a large chakra reserve, Minato could teach him how to better utilize it in combat. This might involve creating more powerful and complex jutsu combinations. Minato could also introduce Naruto to strategic thinking in battles. He might set up mock battles where Naruto has to think on his feet and come up with creative solutions. And of course, Minato would train Naruto in the use of his signature jutsu, like the Rasengan, but with his own unique twists and improvements.
Tsunade would likely use physical conditioning methods. She might have Naruto run long distances while carrying heavy weights, similar to the training she did herself to build her strength. This would improve his stamina and overall physical strength for battles.
In some crossover fanfiction, Naruto might be trained by learning new types of jutsu from other fictional universes. For example, he could learn magic from a Harry Potter - like system, which would completely change his combat style.
He might start with basic earth manipulation. Just like how he learned to control his chakra in the original series, he would need to understand the flow of chakra in relation to earth. Maybe he'd practice making small pebbles levitate at first.
Sasuke could be one of the characters to help Naruto. Their combined powers have been shown to be very effective in the original series.