Well, it could be that Izuku goes back in time and tries to change the way he became a hero. In the original story, he had a tough time at first. With Momo by his side this time, things could be different. Momo might be able to provide resources or support that Izuku didn't have before. And as Izuku tries to change his own hero journey, he might also end up changing the entire hero society in ways he didn't expect, all while building a deeper relationship with Momo.
One interesting plot could be Izuku going back in time and using his future knowledge to prevent certain tragedies. For example, he might stop the initial injury that All Might received, which could change the whole course of the story. Another plot could be him going back to his own childhood and being able to train better and earlier, thus becoming an even stronger hero. He could also use his knowledge of future villains to stop them before they become a major threat.
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.
Izuku could use his future knowledge to better utilize his One For All power in the past. For example, he might know exactly when and how to use his different quirks within One For All more effectively. Momo, on the other hand, could use her creation quirk to create things that were not possible or thought of in the original timeline. Maybe she creates new support items for Izuku that enhance his power even more.
Well, in many izuku goes back in time fanfictions, besides Izuku himself, his mother is an important character. He might go back in time to be a better son, protect her more, or even change things that affected her in the past. Another often - seen character is Aizawa. As Izuku's teacher, Izuku could use his time - travel knowledge to impress Aizawa earlier or get more help from him in his hero training. And of course, the villains like Shigaraki could also be involved. Izuku might try to stop Shigaraki from becoming a villain by going back in time and changing certain events that led to his fall.
There are several potential characters. Aizawa could be one. Godlike Izuku could show up in the past and Aizawa might be suspicious of his powers at first but then come to realize his good intentions. Gran Torino is also a possibility. Izuku could learn different things from him in the past. And then there are the other pro - heroes. They might see Izuku as a strange new force but also recognize his potential to do good. His interactions with them could change the course of hero history in this fanfiction.
She could meet her younger self. This would be an interesting encounter as she could offer advice and guidance to her younger version. Maybe she could help her younger self to be less afraid of her powers.
He could change the course of major events. For example, he might prevent the rise of a powerful villain. This would have a huge impact on the entire galaxy. Maybe he could save some characters who died in the original timeline.
One interesting aspect could be that Luke goes back to a time when the Sith were just emerging. He could try to root out the Sith threat before it became as powerful as it did. He might have to be very careful not to disrupt the timeline too much, but his Jedi wisdom could be a great asset in this time - traveling adventure.
In this fanfiction, Sora might change key events. Maybe he could prevent some of the tragedies that occurred in the original story. For example, he could save a character who was lost before.