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.
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.
The Juubi could save Naruto by sharing its knowledge. In the fanfiction, the Juubi might be an ancient and wise being. It could communicate with Naruto on a spiritual level and give him insights or techniques that help him out of a tough situation. For instance, it could show Naruto a new way to use his existing jutsu more effectively, or it could reveal a secret about the enemy that Naruto is facing, allowing him to strategize better and ultimately be saved from defeat.
Maybe through some sort of ancient ritual. In the Naruto universe, there are often powerful and mysterious rituals. It could be that Naruto discovers an old scroll or is guided by a sage to perform a ritual that allows him to bond with the Juubi.
Well, one possible consequence could be that Naruto gains an enormous boost in power. The Juubi is an extremely powerful entity in the Naruto universe. With it, Naruto might be able to easily defeat his enemies. He could also potentially use the Juubi's power to protect his village in ways he couldn't before, like creating super - strong barriers or launching large - scale attacks against threats.
Well, it could be that Naruto's strong will and his connection to all the other tailed beasts play a role. Since he has befriended the other tailed beasts, their combined energy or some sort of spiritual link might attract the power of the Juubi. For example, in some fanfic concepts, the tailed beasts' collective consciousness decides to merge their powers with Naruto, which includes the Juubi's power as the ultimate form of chakra.
One scenario could be that Naruto underestimates Kiba at first. Kiba and Akamaru launch a surprise attack using their Fang over Fang technique. Naruto is caught off guard but quickly recovers and creates a wall of shadow clones. Another scenario is that Kiba challenges Naruto in a more strategic battle, like in a forest where he can use the environment to his advantage. Naruto, on the other hand, uses his Sage Mode to sense their movements and counterattacks with his Rasengan.
In a Naruto vs Hinata fanfic fight, Naruto has a lot of raw power. He has the Nine - Tails' chakra and a vast array of powerful jutsu like the Rasengan. However, Hinata is no pushover. She has the Byakugan which gives her incredible vision and predictive abilities. If Hinata could get in close, her Gentle Fist techniques could disrupt Naruto's chakra flow. But Naruto's speed and strength might be too much for her. It really depends on the circumstances of the fight in the fanfic, like if Naruto holds back because of his feelings for Hinata or if Hinata has some new power - up.
In a straight - up power comparison, Goku has the ability to reach extremely high power levels that can destroy planets. But Naruto has the power of the Nine - Tailed Fox and his Sage of Six Paths mode which also gives him immense power. If the fight takes place in Naruto's world, Naruto could use the environment to his advantage, like summoning giant toads or using the terrain. On the other hand, if it's in a more open space like in Goku's battles, Goku could use his flight and long - range attacks more effectively. So it's hard to say who would win definitively.
In my opinion, Kirito and Asuna could potentially win. Kirito has his dual - wielding skills and Asuna is no slouch either. They have fought against powerful bosses in SAO. Naruto is strong, but he might be caught off - guard by their speed and teamwork. Kirito and Asuna have a lot of experience fighting together and could coordinate their attacks well. If they can quickly close the distance and take Naruto out before he can use his more powerful ninjutsu, they could be victorious.