Definitely Sasuke. His rivalry and later friendship with Naruto is a central part of the Naruto story. In a fanfiction about a Naruto force, Sasuke's skills and his unique Sharingan abilities would be very useful.
Rock Lee could also be a great addition. His dedication to hard work and his unique fighting style based on taijutsu would bring a different dynamic to the group. He can inspire others in the force with his never - give - up attitude and his ability to face stronger opponents with just his physical skills.
Sakura should be included too. She has become a very powerful medical ninja and has also improved her combat skills. Her knowledge of medicine can be crucial in keeping the members of the Naruto force healthy during missions.
Boruto is an obvious choice. He and Sarada have a unique friendship in the Naruto universe, and their interactions can add a lot of depth to the story. They could go on missions together or have friendly competitions.
Obviously, Merlin himself. And Arthur could be in it too. Maybe Arthur doesn't initially recognize Tiny Merlin and there are some comical misunderstandings between them.
Kakashi could also be a great addition. As a mentor figure, he could guide Sakura in understanding and controlling her newfound powers from her rebirth. And then there are the villains. Orochimaru could be interested in Sakura's rebirth if he senses some new and powerful chakra within her. He might try to capture her for his own experiments.
Well, in a Naruto - One Piece crossover, characters like Luffy and Naruto would be a must. Zoro could learn some sword - based jutsu from Naruto. And Nami might be interested in the ninja tools Naruto uses for stealth and thievery prevention on the ship.
Most likely Naruto would be one of the main characters. Since it's in the name. He would probably be the one exploring the Force and how it works in his world.
A wise old mentor figure could be interesting. This character could be human and have a lot of knowledge about the world that they can pass on to the non - human protagonist. For example, a retired professor who has studied anthropology and can help the non - human understand human cultures.
A group of thieves could also be included. They might initially try to steal from the Prince of Darkness but end up getting caught in his web of power and secrets. Their street - smart skills and lack of scruples could create some interesting dynamics as they interact with the Prince and other more noble characters.
Obviously, Sakura herself is a must - include. Then, characters like Kakashi could be involved as he has Anbu experience. Naruto and Sasuke might also make appearances, maybe Naruto trying to help Sakura in her Anbu - related adventures, and Sasuke being a bit of a wildcard. Additionally, some original Anbu characters could be created, like a veteran Anbu agent who becomes Sakura's mentor in the Anbu world.
A powerful Raikage - like character as an OC would be great. This character could be extremely strong in physical combat and have a no - nonsense attitude towards protecting Kumogakure.
The nosy neighbor can be an interesting addition. They might have their own opinions on whether the couple should love their home or list it. Maybe they're jealous and want the couple to move, or they could be overly attached to the neighborhood and try to convince them to stay.