Well, if Naruto had the Infinity Gauntlet, the story would change drastically. First, he could easily defeat his enemies like Madara or Kaguya with just a snap. No more long and arduous battles. Second, the power dynamic in the ninja world would be completely shifted. Naruto might use the gauntlet to bring true peace, not just the temporary peace they had before. He could potentially reshape the world according to his ideals without having to convince others through his usual means of talk and fight. Third, his friends might view him differently, perhaps with a bit of fear or awe. But Naruto being Naruto, he would still try to use the power in a positive way, but it would be a whole new ball game in the Naruto universe.
He might find it in a hidden chamber in Hogwarts. Maybe it was left there by a powerful wizard from long ago who had some connection to other universes.
One possible plot could be that Naruto uses the Infinity Gauntlet to bring peace to the ninja world. He might snap his fingers and make all the hatred and grudges disappear. With the power of the Infinity Stones, he could also restore all the lives lost in the previous wars, like bringing back his parents and all the fallen shinobi. This would completely change the power dynamics in the Naruto universe and lead to a new era of unity among the different villages.
In this fanfiction, his biggest threat could be Sasuke. Sasuke has always been Naruto's rival and he might see Naruto with the Infinity Gauntlet as a threat to his own goals. He could try to take the gauntlet from Naruto to either use it for his own means or to stop Naruto from misusing it. Another potential threat could be Orochimaru. He is always after power and the gauntlet's power would be too tempting for him to resist. He would surely plot to steal it from Naruto.
Well, in this fanfiction, perhaps the Infinity Gauntlet is brought into the Naruto world by a mysterious portal. Naruto, being the curious and brave ninja he is, picks it up. He might initially struggle to control the stones' powers as they are different from chakra. But as he learns, he could use it to unite the shinobi clans in a way never seen before, like using the Time Stone to show the clans the history of their pointless feuds and convincing them to work together for a better future.
Naruto would become more confident, not just in his abilities but also in his decision - making. Having the Infinity Gauntlet gives him an edge that no one else has. He might become a bit more reserved as he has to be careful with the power he wields. He can't just rush into things like he used to.
Naruto would likely see it as a new way to protect his village and friends. He's always been about that - protecting what he loves. But he'd also be cautious because he knows that power can be dangerous. He might think about how to use it in a way that doesn't corrupt him, like how he was careful with the power of the Nine - Tails.
Madara Uchiha could be a great antagonist. He already has powerful jutsu and a thirst for power. If he gets wind of the Infinity Gauntlet, he would surely try to take it for himself to achieve his goal of creating a world under his control.
In a Batman Infinity Gauntlet fanfiction, Batman would face a moral dilemma. The power of the gauntlet is immense and corrupting. He would have to struggle with whether to use it for what he believes is the greater good or to resist its allure completely. He could also encounter other powerful beings from the DC universe who either want to take the gauntlet from him or help him control its power.
If Spider - Man has the Infinity Gauntlet in fanfiction, he would likely use it to protect his loved ones first. He could use the Soul Stone to ensure the safety of Mary Jane, Ned, and Aunt May. His approach to using the gauntlet would probably be different from someone like Thanos. Spider - Man is all about protecting the little guy, so he'd focus on using the power for the benefit of ordinary people. He might even use the Stones to improve living conditions in the city, like using the Power Stone to generate clean energy for everyone.