Definitely Naruto. Then, Deidara could be an interesting character in this. His explosive personality and unique art of combat could influence Naruto in some ways. He might teach Naruto some of his skills while also getting frustrated with Naruto's different approach to things. Sasori could also be a part of it. His puppet - making skills and his cold, calculated nature could add an element of mystery to how Naruto is raised within the Akatsuki.
Pain could also be a major character. His ideology and the Akatsuki's goals under his leadership might be affected by the presence of baby Naruto. He might see Naruto as a potential threat to his plans or as an opportunity to change the Akatsuki's path. Also, Konan might be involved as she often has a more empathetic side compared to some of the other Akatsuki members and could play a role in taking care of the baby.
Obviously, Nagato himself would be the main character interacting with Naruto. He would be like a mentor or a guardian figure in Naruto's life.
Obviously Naruto and Naruko will interact a lot. But also, characters like Iruka sensei might play a role. Iruka was important in Naruto's life, and he could also be a positive influence on Naruko. And Naruto's friends like Shikamaru, Choji, and Ino might interact with Naruko as well. They could be like her aunts and uncles, teaching her different things and having fun with her.
Obviously, Obito is one of the main characters. He has a complex backstory and his presence is bound to have a big impact on the Akatsuki.
Obviously, Sakura would be one of the main characters. And the members of the Akatsuki would also be important. For example, characters like Itachi or Pain might play significant roles as they are key figures in the Akatsuki. They could be mentors or antagonists to Sakura depending on how the story is written.
In the 'akatsuki watch battle of gods fanfiction', the Akatsuki members are bound to be the main focus. This includes Sasori, Deidara, and Hidan. However, when it comes to the 'Battle of Gods' part, characters like Whis, who is Beerus' attendant, could also play a significant role as the Akatsuki observe the interactions and battles among these Dragon Ball characters.
Sakura and Sasuke are very likely allies. Sakura has her medical skills and combat abilities, and Sasuke, despite his past issues, has great power. They've been comrades with Naruto for a long time.
Another pair could be Naruto and Kisame. Kisame is a very loyal member of the Akatsuki. If Naruto were to interact with him, he might be able to break through Kisame's loyalty to the Akatsuki's more extreme ideals and show him a different path. Their connection could be based on Naruto's unwavering belief in friendship and Kisame's longing for something more meaningful in his life.
Well, the sister herself is a main character, of course. She might be a new addition to the Akatsuki world with her own set of skills and a personality that stands out. Then there would be the well - known Akatsuki members like Itachi or Kisame. They could interact with the sister in different ways, for example, Itachi might be suspicious of her at first, while Kisame could be more laid - back in his approach to her.
Typically, the main characters would be the members of the Akatsuki like Itachi Uchiha. His character is often central in many fanfictions as he has a complex backstory and his actions are closely related to the Akatsuki's goals.