Saitama's laid - back personality would be a contrast to the more intense and passionate heroes in My Hero Academia. He might seem uninterested at times, but deep down he has a strong sense of justice. This could make for some interesting interactions, like when he casually brushes off the fame that comes with being a hero in the My Hero Academia world.
Saitama's overpowered strength would likely be a huge disruptor in the MHA world. His simple yet extreme power of being able to defeat any enemy with one punch would make him a top - tier hero instantly. Genos, with his advanced cybernetic enhancements, would also be quite formidable. He could potentially be part of the development of new support items or hero gear in the MHA universe, given his knowledge of technology. And his combat abilities would put him in the ranks of the stronger heroes there.
Saitama's overpowered nature would completely disrupt the power balance in the MHA universe. His simple yet extreme strength and speed would make him an outlier. For example, in MHA, most heroes have to strategize and work in teams against villains. But Saitama could just one - punch most threats away. This would change the way villains operate as well, perhaps making them more desperate or more likely to target Saitama directly. It could also lead to interesting scenarios where heroes might be both in awe and a bit intimidated by his presence.
Batman in the My Hero Academia world would likely be a bit of an outsider at first. His dark and brooding nature might contrast with the more colorful and often optimistic characters in MHA. However, his intelligence would be highly respected. He could use his detective skills to help solve some of the mysteries that pop up in the MHA world, like the origin of certain quirks or the identity of villains who are hiding in plain sight. And his martial arts expertise would make him a formidable opponent in battles against villains.
Well, he would probably be the most overpowered character. He could easily defeat any villain with a single punch. His presence would disrupt the power balance in the My Hero Academia world. For example, the hero rankings would be completely shaken up as he'd outperform everyone effortlessly.
Deadpool would be a wild card. His regenerative abilities would make him seem like he has a quirk similar to Recovery Girl's but on steroids. He'd likely not follow the normal hero - society rules. For instance, he might start fighting villains in the middle of a civilian - filled street just because he felt like it. His presence would also disrupt the power balance as he has a vast array of weapons and combat skills that are not typical in the My Hero Academia world.
Saitama's personality would be an interesting addition to the Fairy Tail universe in fanfiction. He is often very nonchalant about his power and achievements. In a world where power and magic are highly valued and often flaunted, his indifference could be both refreshing and confusing to the Fairy Tail characters. He might not get caught up in the guild rivalries as much as the others, and his simple desires, like just wanting to find a good sale at the market, could amuse the more grandiose - thinking Fairy Tail members.
The Doom Slayer could be a mysterious figure in the My Hero Academia fanfiction world. He might be from a parallel dimension where his fight against demons is similar to the heroes' fight against villains. He could team up with the likes of All Might or Deku, teaching them about his unwavering determination. His presence would add a new level of intensity to the battles, as he doesn't hold back and is used to facing much more terrifying foes than the average villain in My Hero Academia.
Saitama as a teacher in MHA fanfiction could have a big impact. For one, his laid - back attitude would be a contrast to the more intense and rule - bound teaching in the regular MHA school. He could teach his students the value of not overthinking and just relying on pure strength and quick reflexes. However, he might also struggle with some of the more academic parts of teaching, like explaining quirk theory, since his own power doesn't really come from a quirk.
In a fanfiction scenario, the Hulk might be a result of a secret experiment by the League of Villains to create an ultimate weapon. But instead of being fully controllable, he breaks free and becomes a wild card in the power dynamics of the My Hero Academia world. His presence would disrupt the existing balance between heroes and villains as everyone tries to either control or destroy him.
Sakura Haruno might enter the MHA universe through some sort of multiverse portal. Once there, her strong - willed and determined nature would make her a great hero - in - training. She could learn to use her physical strength, which she had developed in the Naruto world, in combination with a new MHA - style quirk. For example, she could have a quirk that enhances her strength even further when she focuses her chakra (or a similar energy concept in MHA). This would make her a formidable force against villains.