One possibility is that Naruto, with his godlike abilities, could completely rewrite the history of the ninja world. He could go back to the time of the Sage of Six Paths and learn from him directly. This would give Naruto an even greater understanding of chakra and ninjutsu. He could then introduce new forms of training and cooperation among the ninja villages, perhaps even preventing future wars. He could also ensure that the jinchuriki are treated better in the past, changing their fates for the better.
If godlike Naruto goes to Hogwarts in fanfiction, it would be a total chaos in a good way. Naruto is known for his determination and ability to make friends. He would quickly befriend many students. His chakra and ninjutsu would be a new and strange concept to the wizards. He could even use his Shadow Clone Jutsu to attend multiple classes at once, which would amaze the professors. Also, his experience in battles would make him a great asset in protecting Hogwarts from any potential threats.
Well, he would have a second chance at life. Since he was a baby, he could grow up with different relationships. He might form stronger bonds with his parents and be able to learn more about his family. Also, he could start training earlier and become an even more powerful ninja. With his knowledge from the future, he could also help the village in new ways, like coming up with better strategies against enemies.
Well, he could potentially change a lot of things. Maybe he would prevent some of the tragedies that happened in the original timeline. For example, he might stop the Uchiha massacre. He could also use his knowledge of future events and the power of the Juubi to make the ninja world a more peaceful place from the start.
Well, in such a fanfiction, the characters might try to change past events. For example, Naruto could prevent some of the early tragedies in his village. Maybe he'd stop the Nine - Tails attack by somehow convincing his father not to sacrifice himself. This would change the whole future of the village and the relationships between characters.
Well, if Naruto and Juubi go back in time, the storyline could be completely rewritten. For example, Naruto might use his knowledge of future events to prevent some of the tragedies that occurred. He could stop certain villains from rising to power earlier. And with Juubi by his side, he would have an incredibly powerful ally. This could change the power dynamics in the ninja world from the very start.
One possible plot could be that godlike Izuku uses his newfound powers to go back and prevent certain tragedies in the past. For example, he might stop the initial attack that led to so much chaos in his world. He could also use his knowledge of the future to help his friends earlier, like giving Midoriya tips on how to control his quirk better from the start.
Well, he'd probably shock everyone. His ninja skills like super speed and shadow clones would be a wild contrast to the magic at Hogwarts. He might make friends easily as he's used to being part of a team in his own world. And he could teach the Hogwarts students some of his combat skills in return for learning magic.
Well, he might prevent some of the villains from ever becoming powerful. For example, he could stop Frieza from getting all those power - ups.
In the 'Petunia Goes Back in Time' fanfiction, she might try to change things that happened in the past. Maybe she wants to fix a mistake or prevent a bad event from occurring.
In this kind of fanfiction, Jotaro might change some crucial events. For example, he could prevent some of his friends from getting hurt or even stop the main villain from starting their evil plans at an earlier stage. This would completely change the original story's timeline and create a whole new set of adventures and challenges for Jotaro and the other characters.