Well, Naruto and Hiruzen are the central figures for sure. Additionally, characters like Jiraiya could still be involved. Jiraiya might come back to the village and be surprised to see Naruto being trained by Hiruzen. He could then add his own unique training methods to what Naruto has already learned from Hiruzen.
The main characters would be Naruto and Hiruzen. However, we might also see characters like Kakashi make an appearance. Kakashi could be a bit jealous at first that Hiruzen is taking Naruto under his wing, but then he might see the benefits and offer his own advice to Naruto on the side.
Obviously, Naruto and Hiruzen would be the main characters. Naruto as the apprentice and Hiruzen as the mentor.
Obviously, Naruto and Asuma would be the main characters. Naruto, the protagonist of the Naruto series, is the one being trained. And Asuma, a respected jonin in the Hidden Leaf Village, is the trainer.
Obviously Naruto would be one of the main characters as the title implies he is being trained. And then, the RWBY characters like Ruby, Weiss, Blake and Yang would also be main characters since they are the ones doing the training.
Obviously, Naruto and Tenzo would be the main characters. Naruto, as the one being trained, is the protagonist of the Naruto series. And Tenzo, with his unique skills, is the trainer in this fanfic.
In this fanfiction, perhaps Hiruzen realizes Naruto's potential much earlier and decides to train him privately. He might take Naruto on secret missions to build his experience and confidence. This would not only strengthen Naruto's skills but also their bond, which could have a huge impact on the village's future.
In a fanfiction where Naruto is trained by Hiruzen, Naruto would likely have a more traditional and disciplined training. Hiruzen could instill in Naruto the values and ethics of being a true shinobi from the very beginning. Since Hiruzen has seen many great shinobi in his time, he could mold Naruto into a shinobi similar to those of the past. This might mean Naruto would be more proficient in basic ninja skills like stealth and intelligence gathering. Also, his chakra control could be improved more rapidly under Hiruzen's guidance, which would enhance his overall combat capabilities.
Obviously Naruto would be one of the main characters as the title implies he is the one being trained. King Kai would also be a major character as he is the trainer. There might also be some cameos or interactions with Dragon Ball Z characters like Goku or Vegeta, since the fanfiction combines the two universes.
Obviously, Naruto and Deadpool would be the main characters. Naruto is the one being trained and evolving into a 'godlike' state. Deadpool is the trainer who brings his own set of skills and personality to the story.
The main characters would surely be Anakin Skywalker and Count Dooku. Anakin is the protagonist in a sense as we would see his development through Dooku's training. Dooku, on the other hand, is the one who imparts his knowledge and skills, and his character would also be explored in terms of his motives for training Anakin.
Obviously, Anakin Skywalker and Revan. Anakin is the one being trained, so he will be a central figure. His growth and development under Revan's tutelage will be a major focus.