Aang from Avatar: The Last Airbender would be an excellent choice. Aang has the ability to bend all four elements, and his connection to the spiritual world could offer Naruto new perspectives on his own chakra. Another good one is Natsu from Fairy Tail. Natsu's dragon - slayer magic and his intense fighting spirit would make for an interesting training partner for Naruto. Additionally, Midoriya from My Hero Academia. Midoriya's analysis of his opponents and his own growth in power could be something Naruto could learn from.
One idea could be to have Naruto train with characters from other popular shonen series like Goku from Dragon Ball. They could exchange training techniques, for example, Naruto teaching Goku about chakra control while Goku shows Naruto how to better use his physical strength. Another idea is to have Naruto cross over with characters from Fairy Tail. The Fairy Tail mages could introduce Naruto to different types of magic-based training that he could incorporate into his ninja training. A third idea would be to have Naruto train with characters from One Piece. They could have a unique training session on a deserted island, learning survival skills from each other.
Sakura is often a popular character in these types of fanfics. Since she is a kunoichi herself in the original Naruto series, it's easy to write about her further training. Hinata can also be a main character, as her gentle yet strong nature can be explored more during kunoichi training.
Well, one could be about a kunoichi learning unique jutsu during her training. For example, she might discover a long - lost water - based jutsu that gives her an edge in battles. Another could involve her training with a mysterious and powerful sensei who has a hidden past related to the main Naruto storyline.
One unique method could be Naruto using chakra to manipulate the weight of the weights during training. So, he might start with a certain amount of weight, but as he gets stronger in chakra control, he can make the weights feel heavier or lighter at will, adding an extra layer of challenge to his training.
Well, it could be really interesting. Naruto's ninja training techniques might be quite different from what Barry is used to. Maybe Naruto would teach Barry how to use chakra in some form, like to enhance his speed even more. And Barry could show Naruto some of his cool Flash moves in return.
In a Naruto trains Hanabi fanfic, the plot could be centered on Naruto introducing Hanabi to new elements of ninja life. Since Naruto has interacted with various ninja from different villages, he could expose Hanabi to different fighting styles and strategies. He might take her on a journey to different training grounds, where she can learn from the environment and face new challenges. This could also lead to Hanabi developing new friendships and alliances, all while becoming a stronger ninja under Naruto's guidance.
The characters might include some lesser - known characters from the Naruto series who get a chance to shine. For instance, Rock Lee could be part of the crazy team, teaching his unique taijutsu training methods to the others. And then there could be a character who is a foreign ninja, bringing in new techniques and a different perspective to the training.
The plot could involve a group of underdog ninjas forming a crazy team. They might start with really wacky and unorthodox training methods, like training on a constantly shifting terrain made by a jutsu. Their goal could be to master a unique and powerful ninja skill that no one has ever seen before in the Naruto universe.