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.
Well, perhaps Naruto could be sent to King Kai's planet for some super intense training. He might learn unique ki - based techniques similar to those in Dragon Ball Z. Maybe he'll also meet some of the Dragon Ball Z characters there and have some epic battles or training sessions together.
Bulma is a likely main character. She's always been part of the group and would bring her intelligence and her gadgets to the beach setting. Gohan too, as he often gets involved in the group's adventures. His kind nature would make him a great character to have around on the beach, helping others and having fun.
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.
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 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.
Goku and Vegeta are likely to be main characters. They are the two most powerful Saiyans and often at the forefront of any major threat in the Dragon Ball Z universe. Also, Piccolo, as one of the smartest and powerful characters, would probably play an important role.
The main characters are Goku, a Saiyan who is the hero of the story. Vegeta, another Saiyan who starts as an enemy but later becomes an ally. Gohan, Goku's son. Piccolo, a Namekian. Krillin, Goku's best friend. And Bulma, who is important for inventing things that help the characters in their battles.
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.
Well, obviously the Supreme Kai would be one of the main characters. They are central to the fanfic's premise.
Vegeta could also work well. Vegeta's pride and determination, along with his powerful fighting skills, would contrast nicely with the Supreme Kai's more reserved and wise nature. They could learn from each other and have some intense rivalries within the story.