Sasuke is often a popular character in these fanfictions. He might play a role in helping Naruto against Madara or have his own motives during their battle. Kakashi can also be a prominent figure, perhaps using his Sharingan in a crucial moment to assist Naruto. Another popular character could be Hashirama, as his connection to Madara is a key part of the original story and can be further explored in fanfiction.
One interesting plotline could be Naruto discovers a new form that gives him an edge over Madara. For example, a form that allows him to nullify Madara's Sharingan abilities. Another could be Madara having a change of heart due to Naruto's unwavering belief in him. Maybe he starts to question his own motives for destruction.
Naruto would probably win. He has an indomitable will and has always found ways to overcome powerful foes. His experience and the unique powers he might gain with the Rinnegan could give him an edge over Madara.
In such a fanfiction, Naruto and Sasuke might win. They are both extremely powerful and their combined strength, like Naruto's Rasengan and Sasuke's Chidori, could overpower Madara.
Another theme is redemption. Sometimes in these fanfics, Madara has a chance at redemption through his fight with Naruto. Naruto's belief in people's goodness can influence the outcome in such scenarios.
In this kind of fanfiction, Naruto being 'godlike' gives him a huge advantage. He might have powers far beyond his normal capabilities. So, Naruto would likely win. He could use his super - enhanced Sage Mode, or maybe some new jutsu that he has acquired in this 'godlike' state to overpower Madara.
In this fanfiction, 'godlike naruto' might have the power of absolute healing. No matter how severe the injury, he could heal instantly. He could also have the power to absorb and redirect any chakra - based attacks that Madara throws at him. This would make him almost invincible in the fight against Madara.
Madara could also save Naruto by using his knowledge of the ninja world. Maybe he has some inside information about a plot against Naruto and he intervenes in time to stop it. He might have discovered a secret plan by an enemy group and takes action to keep Naruto out of harm's way. This could involve manipulating events behind the scenes or directly confronting the threat.