Harry's magic would be a game - changer. He could use Apparition to quickly move around the battlefield and surprise the enemy. His ability to communicate with snakes (Parseltongue) might also be used to gather intelligence if there were any snake - related codes or secrets in the Axis powers. Plus, his experience in fighting dark wizards like Voldemort would give him the strategic edge in combat against the Axis leaders.
Merlin's magic is very old and powerful. It could make Harry more attuned to the natural elements of magic. For example, he might be able to control the weather more easily during battles. His spell - casting could also become more instinctive and less reliant on wands as Merlin's magic was less wand - centric.
The magic of Aphrodite could interact with the protective spells in Hogwarts. Maybe her love - based magic could make the protective spells stronger by creating a positive emotional bond between the castle and its inhabitants. On the other hand, if her magic goes out of control, it could weaken the spells as the strong emotions she brings might disrupt the delicate balance of the existing magic.
He would become more humble. Losing his magic would make him realize that he's not invincible. He'd start to value the people around him more. For instance, he'd be more grateful for Hermione's intelligence and Ron's loyalty.
His magic would probably be seen as something very strange. Most students and teachers would have no idea about magic, so they might think he's just doing really elaborate magic tricks at first. But if he ever had to use his magic to protect someone, it would be a real shock to everyone.
Harry Potter's magic is based on incantations and wands in his world. In Equestria, magic seems to be more instinctive for the ponies. So when Harry arrives, his magic could be seen as very foreign. His magic might not function properly without the right magical environment. For instance, the magic that he uses to apparate might not work in Equestria because the space - time continuum there could be different. He would have to figure out how to make his magic work within the framework of Equestria's magic system, which could be a long and interesting process in the fanfiction.
His magic might be seen as very different. Japanese magic could have its own style and rules, so Harry's spells might seem strange at first. But also, his powerful magic from fighting Voldemort would likely earn him respect.
Batman's brooding and serious personality would likely make Harry more cautious. Batman is all about planning and preparation, and Harry would pick up on that. For example, Harry might start to analyze magical situations more thoroughly before acting, instead of just relying on his instincts.
Deadpool's irreverent personality would likely make Harry less uptight. Harry has always been under a lot of pressure, but Deadpool's carefree and often inappropriate humor could make Harry see the lighter side of things more often.
Harry might have an easier time with spells related to transformation. Just as Poseidon can change the form of water, Harry could be more adept at transfiguration spells. He could also have a natural ability to breathe underwater and perform magic while submerged, which would be a huge advantage in certain situations. This would open up new possibilities for him in both the wizarding world and any underwater adventures he might have.
His magic might develop in a more instinctive and self - taught way. Without the guidance of Hogwarts professors, Harry would have to figure out his magic on his own. He might use it more for survival and self - defense against the threats that Jason's world presents. For example, he could use magic to create barriers or traps to keep enemies at bay.