Definitely Itachi. He has a complex character and his own sense of justice. He might see Naruto as a key to changing the shinobi world in a different way than what the Akatsuki originally planned. Another one could be Kisame. He is loyal to Itachi and would likely follow Itachi's lead in taking care of Naruto.
I think Sasori could also be a key figure. His skills and knowledge could be passed on to Naruto. He might see Naruto as an interesting experiment or a new hope for the shinobi world. And Deidara, who is often paired with Sasori, would also be around and might have an unexpected influence on Naruto's growth.
Pain (Nagato) could be very important. He has his own ideals about peace. If he sees Naruto as a way to achieve a different kind of peace, he could play a major role. Also, Konan, who is always by Pain's side, would be involved. She might be more sympathetic towards Naruto and help in his upbringing within the Akatsuki.
Pein could be another one. As the leader of the Akatsuki, he might see baby Naruto as a means to an end. He could either want to use Naruto for his own grand plans or, in a more interesting twist, be swayed by Naruto's innocence and change his perspective on the Akatsuki's goals.
Pain would be one of the most challenging. His Rinnegan gives him a wide range of powerful abilities like the Six Paths of Pain. Naruto would have to figure out how to counter each of those paths and find a way to reach the real Pain. Itachi is also tough. His Sharingan and genjutsu skills are top - notch. Naruto would need to break free from his genjutsu and then find a way to fight back against his fire - based attacks.
Itachi and Kisame could be a pair with a close bond. Itachi is a very reserved person, but Kisame seems to respect and understand him to some extent. They often work together on missions, and this could be seen as a form of 'family' bond within the Akatsuki. Another possibility is Deidara and Sasori. Despite their differences in art forms, they seem to have a connection. Deidara looks up to Sasori in some ways, like a younger brother might look up to an older one.
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.
Pain would still be a likely candidate. His Rinnegan gives him a powerful and commanding presence. He has the ability to see the big picture and make strategic decisions for the group.
One of the members could be Karin. She has a connection to Sasuke and has unique abilities. She might see Naruto's new Akatsuki as a place where she can use her skills and be part of something bigger. Jiraiya could also be a part of it in some form, perhaps as a mentor figure from the shadows. And Hinata, out of her love for Naruto and her own growth as a shinobi, might be convinced to join the Akatsuki he forms. There could also be some new characters introduced specifically for this fanfiction who have special powers and are drawn to Naruto's vision for the new Akatsuki.
Obviously Naruto himself is the central character. His growth and new abilities would be the focus. Sasuke could also be important. He might have his own development and his relationship with Naruto could be explored further, whether they are friends or rivals again.
Naruto could use his shadow clone jutsu to play pranks. For instance, he could make clones that look like the Akatsuki members themselves and have them do really silly things like dance around in circles or sing out - of - tune. The real Akatsuki members would be really confused at first, thinking one of their comrades has gone crazy.
A female Uchiha in Akatsuki fanfiction may act as a mediator. Since the Akatsuki members often have conflicting personalities and goals, her diplomatic skills, enhanced by her Uchiha upbringing, could be used to keep the peace within the group. For instance, she might use her Sharingan to read the emotions of the members and defuse tense situations.
The plot could also revolve around the Akatsuki protecting Naruto from other threats in the Naruto world. Perhaps there are other forces that see Naruto as a threat, and the Akatsuki, despite their own reputation, step in to keep him safe. This could lead to some interesting battles and alliances, as the Akatsuki has to face off against their former allies or new enemies all while taking care of Naruto.