Obviously, Naruto would be the main character. But there could also be other characters like Shikamaru, who might be his advisor or right - hand man in dealing with the council matters. Sakura could also be involved, perhaps as a medical ninja representative in the new council structure that Naruto creates.
Obviously Naruto would be one of the main characters. He'd be the one to bridge the gap between the Naruto universe and the Jedi Council. Sasuke could also be a main character, his brooding nature might be an interesting contrast to the calm and collected Jedi. And from the Jedi side, characters like Yoda or Mace Windu could be central, as they are important members of the Jedi Council and would be the ones to interact the most with the Naruto characters.
Well, in this kind of fanfiction, Naruto might completely change the way the council operates. He could bring in new rules that are more fair and just for all the ninja in the village. Maybe he would make decisions that focus more on the well - being of the common people rather than just the interests of the powerful clans.
Definitely Naruto himself. He'd be a central character, causing chaos and bringing energy to the daycare. And Sasuke would also be there, probably being a bit of an aloof kid that Naruto is determined to get close to.
I think Kakashi would be an important character too. He could be Naruto's mentor in this new situation, teaching him how to use his remaining abilities effectively. Also, Sakura might be there, using her medical ninjutsu skills to try and help Naruto with his crippled state.
The main characters would surely include Naruto himself. His child or children are bound to be in the spotlight. In addition, any of the Akatsuki members who may have reformed or are still causing trouble could be part of the story. For example, if Naruto's child has some connection to the Akatsuki's past actions or secrets, it could bring them into the plot. Also, the villagers of Konoha, who would interact with Naruto's family, could be important characters in this fanfiction.
Besides Naruto and Sasuke, Sakura could also be a main character in such fanfiction. Her medical ninjutsu skills might be needed to heal the wounded during the battles against Galactus. And there could be some original characters created specifically for the fanfiction who have some special knowledge or power related to Galactus and the Naruto world.
Other Naruto characters like Sasuke or Sakura might also be important. Sasuke could be involved in Naruto's new role as a 'guardian' either as a supporter or a skeptic. Sakura, with her medical skills, could play a role in helping Naruto in his 'guardian' - related adventures, perhaps by healing those affected by new threats that come with the combination of the two universes.
Obviously Naruto and Ophis. Naruto is the main protagonist from the Naruto series, and Ophis is from another fictional context. There could also be some of Naruto's friends like Sasuke or Sakura who might be involved in some way. Maybe they are worried about Naruto when he disappears into Ophis' world.
There could be new characters introduced in this fanfiction. Maybe a mysterious ninja from a far - off land who knows about Naruto's secret and either helps or hinders him. Another possibility is that an old, forgotten character from the Naruto universe is brought back and has some connection to the secret.
There could also be new characters introduced. Maybe a business rival who is jealous of Naruto's success. This rival could be from another village or even an outsider who has his own motives for trying to take down Naruto's billion - dollar empire. And of course, the Hokage would still play a role, as Naruto's actions as a billionaire would have an impact on the village's politics and power structure.