One possible plot could be a crossover where a Saiyan somehow ends up in the Naruto universe during the time of Kaguya. Maybe the Saiyan's power is sensed by Kaguya and she sees it as a threat or an opportunity. The Saiyan, with their battle - hardened nature, could get involved in the Naruto characters' fight against Kaguya, adding a new dimension of power and strategy to the battle.
Perhaps in the fanfic, a Saiyan is sent to the Naruto universe on a mission to study the chakra system, which is very different from their ki - based power. They encounter Kaguya, who is intrigued by the Saiyan's power. The Saiyan then teams up with Naruto and his friends. Naruto, being the main protagonist, tries to understand the Saiyan's way of life and fighting. Together, they face Kaguya, with the Saiyan teaching Naruto some new combat techniques based on their Saiyan abilities.
Well, it could be that the Saiyan is actually a long - lost relative of Kaguya. In this fanfic, the Saiyan's arrival in the Naruto world reveals a hidden connection between the Saiyan race and Kaguya. This connection could change the way the Naruto characters view Kaguya and their own history. The Saiyan might have different views on power and morality compared to the Naruto characters, which could lead to interesting conflicts and alliances.
Well, one possibility could be that Naruto, with his Saiyan powers (assuming some sort of crossover mechanic), has to deal with Kaguya in a new way. Maybe he forms a harem that includes characters related to Kaguya's story. The plot could involve battles against new threats while also exploring the relationships within the harem.
The Saiyan's power is mainly based on their physical strength, ability to transform, and use of ki. Naruto has his chakra, with the Nine - Tails' chakra being a major part. Kaguya has her own powerful chakra and unique abilities like the All - Killing Ash Bones. In a fanfic, the Saiyan's physical might could be a match for Kaguya's brute force attacks. Naruto's chakra - based jutsu could be used to complement the Saiyan's attacks, for example, using shadow clones to create diversions while the Saiyan attacks directly. Kaguya's reality - warping abilities would pose a huge challenge to both the Saiyan and Naruto, forcing them to come up with new strategies together.
Naruto is a must. Kaguya, as a key part of the Naruto lore, would be in it. In terms of the harem, Ino could be one of the characters. She has always had an interest in Naruto to some extent. Tenten could also be part of it, perhaps drawn to Naruto's new Saiyan - like strength. And from the Saiyan side, Raditz could be introduced, creating some conflict as he initially tries to take advantage of Naruto's Saiyan powers but later might become an ally. There could also be some original characters created just for this fanfic.
A possible plot idea is that Naruto discovers a new form of jutsu that allows him to dominate Kaguya's mind. He then uses this power to make her see the error of her ways and help her become a force for good in the ninja world. Also, we could have a plot where Naruto forms an alliance with other powerful ninjas and together they dominate Kaguya, but then have to deal with the moral implications of such dominance.
Well, an interesting plot could involve a fusion of the energy systems in both Naruto and Dragon Ball universes. Naruto, as Super Saiyan Blue Naruto, could be tasked with saving both universes from a threat that is causing the boundaries between the two to collapse. He would have to use his newfound powers, which combine chakra and ki, to stop the chaos and restore balance.
Well, it could involve Naruto having some unique powers inherited from Kaguya. Maybe he discovers his true lineage gradually and has to deal with the expectations and the secrets that come with it. He might face new enemies who are interested in his connection to Kaguya, or he could use his new - found heritage to bring about a new era of peace in the ninja world.
One interesting aspect is the power - scaling. When Naruto is godlike, his abilities are far beyond the normal scope, and seeing how he interacts with Kaguya, who is also extremely powerful, creates exciting battle or cooperation scenarios.
A really cool plot could be a time - travel fanfic. Naruto gets sent back in time to the era of Kaguya. He has to navigate this ancient world, understand Kaguya's motives from the very beginning, and try to prevent the future conflicts that his own era is facing because of Kaguya's actions. This would involve him trying to befriend Kaguya or change her path before she becomes the antagonist we know.
Another concept could be that Naruto is actually part Saiyan in this fanfic. His unwavering determination and ability to keep getting stronger could be attributed to his Saiyan heritage. This would add a new layer of mystery to his character and also open up possibilities for new jutsu or power - ups that are related to his Saiyan side, like a chakra - based Kamehameha - like attack.
Kakashi can be a popular character too. His wisdom and combat skills can be useful in fanfic scenarios involving Kaguya. He could be a mentor figure to Naruto, guiding him in dealing with Kaguya - related threats or helping to decipher ancient ninja knowledge related to Kaguya.