One common crossover idea is a scenario where the Titans from Attack on Titan are considered as 'villains' in the My Hero Academia universe, and the heroes have to come up with strategies to defeat them. It could also be interesting to see how the Quirks in My Hero Academia would be perceived in the world of Attack on Titan. Maybe some characters would be seen as 'demons' because of their unique powers. And then there's the idea of a character from Attack on Titan, like Eren, somehow getting a Quirk in the My Hero Academia world and how that would change his character arc.
One popular idea is to have Goku from Dragon Ball Z face off against the Titans from Attack on Titan. His super strength and fighting abilities would make for an epic battle. Another is to see if the Dragon Balls could be used to somehow stop the Titan invasion. Maybe the Z fighters could team up with the Survey Corps to achieve this.
One idea could be that Kakashi is somehow transported to the My Hero Academia world. He could become a teacher at UA, using his ninja skills and wisdom to train the students in new and unique ways. His Sharingan would be a very interesting power in the MHA universe.
One great place to find My Hero Academia and Attack on Titan fanfiction is Archive of Our Own (AO3). It has a vast collection sorted by various tags like character pairings, genres, and ratings. Another option is Fanfiction.net. There are also some Reddit communities dedicated to fanfiction where users share and discuss their favorite works.
In an 'Attack on Titan' and 'Titanfall' crossover fanfiction, there could be a plot where the world of 'Titanfall' is somehow connected to the world of 'Attack on Titan' through a rift in space - time. The Pilots could be sent to the 'Attack on Titan' world to help in the fight against the Titans. They could introduce their Titan - mech technology to the people there. The story could also focus on the cultural shock that both sides experience. The Pilots would be shocked by the primitive living conditions in 'Attack on Titan' while the 'Attack on Titan' characters would be amazed by the high - tech machinery of the Pilots.
One idea could be that Mel, a character from another universe perhaps, has some unique ability that can help the Survey Corps in 'Attack on Titan' deal with the Titans. For example, if Mel can manipulate time, she could freeze the Titans in place, giving the soldiers a chance to attack without risk. Another idea is that Mel accidentally ends up in the world of 'Attack on Titan' and has to learn the ways of survival there. She could form an unlikely friendship with Eren or Mikasa and together they discover new ways to fight the Titans.
One idea could be that the Soul Reapers have to enter the world of Attack on Titan to stop Hollows that are being created by the Titans' negative energy. Another could be that Eren Jaeger somehow gains Soul Reaper powers and uses them to fight both Titans and Hollows. Maybe Ichigo could end up in the walls and teach the Survey Corps his sword - fighting techniques to better combat the Titans.
One idea could be that Godzilla arrives in the My Hero Academia world during a major villain attack. The heroes initially see Godzilla as a threat but soon realize that he is targeting the same villains who are causing environmental destruction. His massive size and power could be a game - changer in the battle.
A great crossover idea is with the Dragon Ball series. The powerful Saiyans could interact with the My Hero Academia characters. Goku could train the students at UA to reach new levels of power. Also, a crossover with the Attack on Titan world would be intense. The heroes would have to deal with Titans in a whole new way and use their quirks in that battle - filled environment.
A cool My Hero Academia crossover fanfiction idea would be with the Avengers. The heroes from UA could team up with the Avengers to fight a common enemy. For example, a powerful villain who can absorb quirks and powers. It would be interesting to see how characters like All Might and Captain America interact, and how their leadership styles differ.
One idea could be a crossover with the Naruto universe. The characters from My Hero Academia could interact with Naruto characters. For example, Deku might learn some new fighting techniques from Naruto. Another idea is a crossover with the Harry Potter world. The students at U.A. could visit Hogwarts and experience magic, while the Hogwarts students could learn about quirks.