In many BNHA fanfictions where Izuku meets All Might early, it often changes the entire trajectory of Izuku's development. For example, he might gain confidence much sooner. Early meetings can also lead to a more in - depth mentorship that might deviate from the original storyline. This could result in Izuku getting special training earlier and potentially unlocking his Quirk in a different way.
It might be a story where they meet in a multiverse - type situation. All Might could be visiting Superman's world for some reason, like to learn about different forms of heroism. At first, there could be misunderstandings due to cultural differences between the two universes. For example, All Might's very public and flamboyant hero persona might be a bit strange to the more reserved Metropolis citizens. But eventually, they find common ground in their desire to protect the innocent and start to work together on some local threats in Superman's world.
Their powers could interact in interesting ways. All Might's 'One For All' power is more about physical enhancement within the limits of a human - like body (even though he is super - human). Superman's powers are more 'alien' in nature. If they were to exchange power - up techniques, All Might could teach Superman some of his martial arts moves, which Superman could then use with his super - strength. In return, Superman could show All Might how to better control his power output in different situations using his knowledge of his own powers which are more energy - based in some aspects.
Well, they could start off on the wrong foot. Tony, being the genius billionaire playboy philanthropist, might initially underestimate All Might. But once he sees All Might in action, he'd be impressed. They might end up having a friendly competition to see who can save more people in a given time. Or perhaps they'd combine their resources. Tony could upgrade All Might's costume with some Stark tech, like adding some energy - absorbing or flight capabilities. And in return, All Might could show Tony some of his combat techniques that don't rely on high - tech gadgets.
In this fanfiction, Izuku might gain confidence earlier. Since meeting All Might earlier could potentially change the course of his initial self - doubt. He could start his hero training sooner and have a different growth trajectory compared to the original story.
One consequence could be a faster growth in Izuku's power. With All Might's early guidance, Izuku may master his Quirk more quickly. Another is that his relationships with other characters might change. For example, Bakugo could become more jealous or, on the contrary, might be inspired to work harder.
It's hard to say. Tony Stark has his high - tech gadgets and intelligence. He can quickly analyze situations and come up with strategies using his suit's various functions. But All Might has incredible physical strength. In a direct physical fight, All Might might seem more dominant at first. However, Tony could use his smarts to find weaknesses in All Might's opponents or in All Might himself if they were to ever face off. So it really depends on the situation and how the writer wants to portray their encounter.
It could be the First Hokage, Hashirama. Naruto would be amazed by his powerful Wood - Style jutsu and his ability to create the village. He could learn about the original ideals behind the Hidden Leaf from Hashirama.