The other Jinchuurikis could be potential allies. They understand the struggles and the power that comes with having a tailed beast inside them. For example, Killer Bee, who has a good relationship with his tailed beast, could share his insights on how to better co - exist with Shukaku. Tsunade might also be an ally, as she is a powerful Hokage who could offer protection and resources to the Jinchuuriki.
I would recommend 'Naruto and Shukaku: A New Alliance'. In this fanfiction, it focuses on a scenario where Naruto and Shukaku have to team up against a new, powerful enemy. It has a lot of action scenes and also some really interesting character development for both of them.
Boruto could be developed by showing his growth in responsibility. For example, in the fanfic, he could take on the task of teaching Himawari a new jutsu. This would not only show his skills but also his patience. Himawari, on the other hand, could be developed by showing her becoming more independent. Maybe she decides to go on a small mission on her own to prove herself to Boruto.
Good fanfiction in this regard also pays attention to the lore of the Naruto universe. It should be consistent with the rules about chakra, jinchuriki, and the world - building already established in the original series. If it just ignores all these elements, it won't feel like a proper 'naruto and shukaku' story.
One interesting Naruto Shukaku fanfiction could be about Shukaku's backstory before being sealed into Gaara. It might explore how it lived in the desert and its interactions with other beings there.
One idea could be a story where Himawari discovers a new ninja technique and Naruto helps her perfect it. They could have training sessions together, and Naruto shares his own experiences from when he was learning new jutsus. This would strengthen their bond as father - daughter and also show Himawari's growth as a ninja in - training.
Obviously Naruto would be the main character. Shukaku itself or a representation of Shukaku's spirit could be there. Also, characters like Iruka sensei would still be around. His friends like Sasuke and Sakura would play important roles as they react to Naruto's new situation.
Well, it could be about Naruto having the powers of Shukaku in addition to his own. Maybe he has to learn to control this new power source and face new enemies who are after his unique abilities.
One interesting storyline could be about the relationship between the Shukaku and Naruto evolving in a unique way. For example, the Shukaku might teach Naruto some ancient and powerful jutsu that was once known only to the tailed beasts. This could give Naruto an edge in battles and also deepen their bond.
Naruto would win. He has a lot of experience fighting powerful opponents and has developed many powerful jutsu over time. He also has the willpower and the ability to adapt in battle. Shukaku is strong, but Naruto's intelligence and his ability to think on his feet would give him the edge.