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.
His quirk could be something like 'Limitless Rage - Transformation'. When he gets angry, his body transforms into the Hulk form, growing in size and strength. The angrier he gets, the more powerful he becomes, similar to how it works in the Hulk's original story.
Goku could be seen as an alien with an extremely powerful 'Quirk' in the My Hero Academia world. His Saiyan abilities like flight, super strength, and energy blasts could be considered a new type of Quirk. He would likely stand out a lot and attract the attention of both heroes and villains.
One way it could fit is by having a character with a quirk that allows them to mimic the Sharingan's abilities. For example, they might be able to copy other heroes' or villains' quirks in a similar way to how the Sharingan can copy jutsu in Naruto. This would add a whole new level of strategy and intrigue to the My Hero Academia world.
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.
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.
Gohan could fit in by being a transfer student. His Saiyan powers would be seen as a very unique 'quirk'. In the harem aspect, his kind heart would draw the attention of the female characters. For example, Mina would find his positive attitude infectious.
First, think about their Saiyan powers and how they would translate in the My Hero Academia world. For example, a Saiyan's ability to increase power level could be like a quirk that gets stronger over time. Consider their backstory, like maybe they're a Saiyan from another planet who ends up in the MHA world. Also, their appearance can combine Saiyan features like a tail and spiky hair with the MHA style of clothing.
The Infinity Gauntlet would likely cause chaos. In My Hero Academia, society is built around the concept of Quirks and how they are used. If the Infinity Gauntlet entered this world, it would introduce a new form of power that is not based on genetics but on an external, extremely powerful object. This would disrupt the existing balance between heroes and villains. Villains might see it as a way to finally achieve their goals of domination, while heroes would have to figure out how to deal with a power that is far beyond what they are used to facing.
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.
She could be a transfer student from another hero academy with her own set of unique skills. Her powers would likely make her stand out among the MHA students.