Well, if Deku was in Todoroki's body, his training would be a lot different. Deku is used to his own body's limitations and the way his quirk works in it. In Todoroki's body, he would have to get used to Todoroki's balance of fire and ice powers. He might initially struggle with the dual - natured quirk as it's very different from his own. On the other hand, if Todoroki was in Deku's body, he would have to deal with Deku's lack of natural power control at first. Deku has had to train hard to master his quirk, and Todoroki would need to adapt to that different level of starting ability.
For Deku in Todoroki's body, training could become more about mastering the combination of two powerful elements. He would need to learn how to blend the fire and ice in a more seamless way than Todoroki perhaps has. He might experiment with new techniques that Todoroki hadn't thought of. As for Todoroki in Deku's body, he would be facing a quirk that is more about building up strength gradually. He would have to adjust to the physical toll that Deku's quirk takes on his body during training. He might also have to work on his own mental approach, as Deku has a very different mindset when it comes to training compared to Todoroki.
When Deku is in Todoroki's body, his training might involve more strategic use of the fire and ice powers. He could focus on using the ice to create barriers during combat training and the fire for offensive moves in a more coordinated way. Since Todoroki has a more natural affinity for these powers, Deku would be exploring new ways to utilize them. In contrast, when Todoroki is in Deku's body, he would be learning about the nuances of Deku's quirk. He would need to practice the proper form and build - up of power that Deku has been working on. He might also start to understand the importance of Deku's physical conditioning in relation to his quirk better during training.
A great plot twist might be related to their relationships. While in each other's bodies, they could accidentally say or do things that affect their relationships with other characters. For instance, Todoroki in Deku's body could unknowingly say something to Ochaco that makes her misunderstand Deku's feelings. Also, they could find it difficult to interact with their families in the other's body. Deku might not know how to handle Todoroki's father in Todoroki's body, leading to some tense situations.
I think Iron Man and Hulk would be a really interesting pair. Just imagine Tony Stark's brilliant mind trapped in the Hulk's huge, rage - filled body. He would be constantly trying to find a way to control the Hulk's strength and not go on a rampage. And Hulk in Tony's body would be so confused by all the technology and might accidentally set off some of Stark's weapons.
Ron would probably be really confused at first. He might think it's some kind of elaborate prank by Fred at first, but when he realizes it's something more serious, he'd be worried. Harry would be more level - headed and try to figure out how to help them switch back. Ginny might find the whole situation quite funny, especially seeing Hermione in Fred's body trying to act like a boy. She might give her some tips on how to fit in better as a male Gryffindor.
On the other hand, a boisterous boy in a girl's body might become more reserved. He'll quickly realize that girls are often expected to be more demure in society. So he may tone down his loud behavior and become more aware of his body language and the way he speaks.
In a body - switch scenario, Harry in Hermione's body would probably have his personality shift towards being more detail - oriented. He'd pay closer attention to the little things, like Hermione does when she's studying spells or researching. He might also become more critical of himself in terms of academic performance. Hermione in Harry's body, though, would gain a bit of Harry's recklessness. She'd be more willing to take risks without fully thinking through the consequences. But at the same time, she'd still retain her intelligence, so she might use it to calculate risks better than Harry usually does. This switch of personalities could lead to some really interesting character interactions and growth throughout the fanfiction.
Well, in terms of relationships, if Harry and James switch bodies, Harry in James' body would have a new perspective on his father's relationship with Dumbledore. He might question some of the things Dumbledore asked James to do. And James in Harry's body would have to deal with the complex relationship Harry has with the Dursleys. He would probably be much more assertive in dealing with them compared to Harry. Also, the relationship between Harry - in - James' body and the other Marauders would be interesting. He might try to nudge them towards better decisions, changing their relationships in the long run.
Pikachu, Ash's main Pokémon, would be very confused. It's used to Ash's mannerisms and commands. When Serena is in Ash's body, Pikachu might not respond as well at first. It might keep looking at 'Ash' quizzically, wondering why he's acting so strange. Serena's Pokémon, like Braixen, might also be confused. They might sense that something is off with 'Serena' (Ash in her body) and be a bit hesitant to follow commands as usual.
There could be a scientific experiment gone wrong. For example, they are in a lab for some school project on teleportation or something similar. But instead of teleporting, their minds or consciousness get transferred to each other's bodies. Another way could be through some kind of alien technology. An alien device that was meant for something else malfunctions and causes their bodies to switch.
Max in May's body would have to adapt to her more empathetic and relationship - focused personality. He might not be used to being so in tune with others' emotions and could make some blunders at first. May in Max's body would have to tone down her exuberance a bit and deal with Max's more studious and detail - oriented side. She would need to be more logical in her decision - making, which could be a challenge for her.
Well, Ash is very determined and brave. In Pikachu's body, this might make Pikachu seem more fearless in battles. He might take on stronger opponents without hesitation.