Well, it could be that Naruto uses his new Sage of Six Paths powers to combat the Juubi. Maybe he has to find a way to break through the Juubi's defenses which are super strong. He might also get some help from his friends at some point in the fanfic.
One idea for the 'naruto vs juubi fanfic' is that the Juubi has some sort of mind - control ability. It starts to take over some of Naruto's friends, forcing Naruto to hold back in his attacks. Naruto has to find a way to break the mind - control while also dealing with the Juubi's powerful physical attacks. He could try to use his Rasengan in a new and creative way, like infusing it with his positive chakra to counter the Juubi's negative energy.
A plot might involve Shukaku being controlled by an evil force and Naruto has to fight it to save the village. Naruto starts by trying to reason with Shukaku, but when that fails, he has no choice but to engage in a fierce battle. He might call upon the help of his friends like Sasuke or Sakura at some point to create a strategy to defeat Shukaku.
One possible plot could be that Naruto somehow gets involved in the Sekirei Plan while still having the power of the Juubi within him. He might use his ninja skills and the Juubi's power to protect the Sekirei from those who would use them for evil purposes. For example, he could face off against Minaka Hiroto, the creator of the Sekirei Plan, if he discovers that the plan is causing harm to the Sekirei. Naruto's values of friendship and protecting the weak would likely drive his actions in this fanfic scenario.
Another plot could revolve around a character from the Selda universe who gains the power of the Juubi. This new - powered character might initially be corrupted by the immense power but then is redeemed with the help of Naruto's friendship and ninja way. It could lead to an epic battle between good and evil where the values of both Naruto's world and Selda's world are put to the test.
One possible plot could be that the Juubi somehow gets transported to the Naruto world during a strange rift in space - time. Naruto and his friends have to figure out how to deal with this powerful and chaotic entity. They might initially try to fight it, but then realize they need to find a way to seal it again, like they did with the other tailed beasts. This could lead to new alliances and power - ups for the characters as they struggle to protect their world.
Well, perhaps in the 'naruto vs sasuke the aftermath fanfic', there could be a focus on the physical and mental recovery of both Naruto and Sasuke. Naruto, being the more positive of the two, might bounce back quickly, but Sasuke's internal struggles could be explored in depth. There could also be new threats emerging that they have to face together, which would force them to put aside their differences and cooperate, even if reluctantly at first.
It depends on how the author writes it. But if Naruto has all his powers and the will to win, he could defeat the Juubi. He has shown amazing growth and power throughout the Naruto series.
In a Juubi Naruto meets Rias fanfic, the plot might revolve around a tournament. Naruto is invited to participate in a supernatural tournament in Rias's world. As the Juubi Naruto, he has incredible power which draws a lot of attention. Rias becomes interested in him not just for his power but also his sense of justice. They form an alliance during the tournament and face various challenges together, learning from each other's fighting styles and strategies.
Well, perhaps in the fanfic, Naruto has to team up with his friends in a unique way to seal the Juubi. For example, Sasuke could use his Sharingan to help Naruto locate the weak points of the Juubi while Naruto does the actual sealing. And Sakura could use her medical ninjutsu to keep Naruto in top shape during the process.
Well, it could be about a dark version of Naruto having different goals and values from the original Naruto. Maybe the black Naruto wants to take over the Hidden Leaf Village by any means, while the real Naruto tries to stop him to protect his home and friends.
One possible plot twist could be that Danzo is actually being controlled by an even greater enemy. So, when Naruto is about to defeat him, he realizes that there's a bigger threat behind Danzo. Another could be that Danzo reveals a hidden power that he has been suppressing all along and suddenly becomes much stronger than Naruto expected.