Well, it could be about Ben using his Omnitrix to team up with the heroes from My Hero Academia. Maybe he helps them fight against a new villain that's too powerful for them alone. He could transform into different aliens to use various powers in the battles.
One possible plot could be that the Omnitrix from Ben 10 somehow ends up in the My Hero Academia universe. Ben could team up with Izuku Midoriya. Ben, using his various alien forms, could help in hero battles against villains. For example, Heatblast could be useful against ice - based villains in the MHA world. And Izuku could learn a lot from Ben's experience in handling different powers and situations.
I think Ben and Deku would be an interesting pairing. Deku is all about analyzing and strategizing, while Ben has the power of the Omnitrix. Deku could help Ben figure out better ways to use his alien forms in combat, and Ben could show Deku some really out - of - this - world powers.
Here's a simple start for a 'prototype My Hero Academia crossover fanfic': In a world where the quirks of My Hero Academia exist alongside the powers from 'prototype'. Alex Mercer finds himself in the middle of Musutafu city. He's confused by the sight of people with all these strange abilities. Izuku Midoriya spots this strange man and approaches him. Mercer, being the shape - shifter he is, tries to blend in but his lack of knowledge about quirks starts causing some misunderstandings. As they interact, Mercer realizes that these 'quirks' could be a new form of power to study, while Midoriya is both fascinated and a bit scared of Mercer's abilities.
It could be really exciting. Maybe Ben could use his Omnitrix to transform into an alien with a Quirk - like a combination of his alien powers and a hero's ability from My Hero Academia. For example, he could turn into Four Arms but with super strength enhanced by One For All. The story could involve Ben and the heroes of UA working together to stop a powerful villain that neither could defeat alone.
In a 'Ben 10 My Hero Academia Crossover Fanfiction', Ben Tennyson would be a main character. He has the Omnitrix which is full of possibilities. Another main character could be Ochaco Uraraka. Her gravity - controlling Quirk would be an interesting contrast to Ben's alien powers. They could work together in some really cool ways, like Uraraka using her Quirk to levitate Ben in a strategic way during a battle. And then there's also Tenya Iida. His speed and strict sense of justice would add another dynamic to the group. These characters would all play important roles in the story, whether it's in combat, strategizing, or just in their interactions with each other.
Another possible plot is a competition between Superman and the top heroes in My Hero Academia. They hold a friendly, but intense, competition to see who is the most powerful and heroic. This would not only showcase their different powers and abilities but also how their concepts of heroism differ. It could lead to a lot of character development for both sides as they learn from each other.
One idea could be a crossover with the Harry Potter universe. Imagine Deku going to Hogwarts and learning magic while also using his Quirk. He could make friends with Harry and they could learn from each other's skills. Another idea is a crossover with the Avengers. The heroes from My Hero Academia could team up with the Avengers to fight a common, super - powerful enemy. Maybe All Might and Captain America could have an interesting conversation about leadership and heroism.
One great 'My Hero Academia' crossover fanfiction is the one where they cross over with 'One Piece'. It combines the unique powers of the 'My Hero Academia' world with the adventurous and diverse world of 'One Piece'. The characters interact in really interesting ways, like Midoriya being amazed by Luffy's Devil Fruit powers and Luffy being intrigued by the concept of Quirks.
All Might and Ben would have a great interaction. All Might, being the symbol of peace in the MHA world, would be intrigued by Ben's powers. He might see Ben as a young hero with a different kind of power set. Ben, on the other hand, would look up to All Might's heroism. Also, Ochaco and Ben could have an interesting dynamic. Ochaco's gravity - controlling Quirk could be used in combination with some of Ben's alien forms in creative ways during battles or rescue operations.