Iruka Sensei might also make an appearance. He could be like a grandfather figure to Naruto's child, telling stories of Naruto's days at the ninja academy and teaching the child about the values that Naruto learned when he was young.
Sakura could be there. As Naruto's friend, she might be the child's doctor, always ready to heal any injuries. She could also give parenting advice to Naruto based on her medical knowledge.
Well, surely Hinata would be there. As Naruto's wife, she would support him in his role as Uzukage. Maybe Boruto and Himawari would also be involved, learning about their Uzumaki heritage from their father. And there could be some other Uzumaki clan members who have been in hiding and now come out to help Naruto lead the village.
Well, all the regular Naruto characters would still be there. Sasuke could be a major character. He might be initially skeptical or even jealous of Naruto's new identity. Kakashi could also play a role, perhaps trying to help Naruto control his new powers. And from the Shiva side of things, Nandi, Shiva's bull, could be a character. He could act as a protector or a guide to Naruto, teaching him about Shiva's ways and powers.
Sasuke could be in it. He might be initially skeptical of Naruto's new power but then see its potential in combat.
The Daimyo of Wave himself would be a main character for sure. Also, his guards or advisors who have a say in the running of Wave. Maybe a young heir to the Daimyo who is being groomed to take over and has his own ideas about the future of Wave.
Sasuke could be a main character. He might be initially interested in the dragon egg for its power but then his relationship with Naruto over the egg could change. Maybe they start as rivals again, but then realize they need to work together to protect the egg.
Sasuke could be one of the main characters. He might be the one who comes across Naruto in his boxers and has a very typical Sasuke - like reaction, which could be a mix of annoyance and amusement. His presence could add some tension as well as some banter to the story.
Sakura could be one of the performers, showing off her medical ninjutsu skills in a unique and entertaining way. Sasuke might be a brooding figure who is part of a dangerous acrobatic act. And Kakashi could be Naruto's adviser, helping him run the circus behind the scenes.
There could be Sasuke. Since Sasuke is Naruto's rival and often involved in the same major story arcs, he might play an important role in this fanfiction. His sharingan abilities could interact with Naruto's newfound speed in some interesting ways, either as an ally or an obstacle depending on the plot.
There could be some new characters introduced. For example, an old hermit who has a deep knowledge of ancient trap - making techniques and teaches Naruto some of his secrets. Also, some of the villains from the original Naruto series might appear, like Orochimaru, who would be intrigued by Naruto's newfound skills and try to either steal them or find a way to counter them.
The Hokage, of course. Depending on which era the fanfiction is set in, it could be Tsunade, Kakashi, or even Naruto himself in some time - jump scenarios. They play a crucial role as Naruto's superior who he serves.