Well, Raiden from Mortal Kombat might be a strong contender. He is a thunder god with incredible powers. In a crossover with Harry Potter, his ability to control lightning could give him an edge. He could use his powers to disrupt the magic of wizards or directly attack them. And his immortality would make him a difficult opponent to defeat, even against the most powerful wizards.
It could be Akuma. His Satsui no Hado gives him incredible power and his fighting skills are top - notch. In a crossover, he could easily adapt to the Mortal Kombat's more brutal fighting style and use his dark powers to overpower many opponents.
It could be Arya Stark. In Game of Thrones, she has proven to be a highly skilled assassin. In a Mortal Kombat crossover, her ability to change faces and sneak up on her enemies would be a great advantage. She could use her Needle sword and her skills learned from the Faceless Men to take on opponents. And her list of names of those she wants to kill could easily be added to with Mortal Kombat villains.
Another strong contender could be Raiden. As a thunder god in Mortal Kombat, he has control over lightning and has great combat skills. In the Harry Potter universe, his lightning attacks could be very difficult to defend against. He could also use his powers to disrupt magic, as electricity can interfere with magical devices. His immortality also gives him an advantage, as he can keep coming back in a fight no matter how much damage he takes.
It's really hard to say for sure. Shao Kahn from Mortal Kombat is extremely powerful with his brute strength and magical abilities. But then you have characters like M. Bison from Street Fighter who has powerful psychic powers. If we consider a crossover, it might depend on the rules of the world they are in. In a world more based on Mortal Kombat's rules, Shao Kahn might have the edge, but in a more Street Fighter - like setting, M. Bison could be more dominant.
Scorpion could also be a top - tier powerful character in this fanfiction combo. His hellfire abilities and his ninja skills are no joke. In a fight against the My Hero Academia characters, he could easily surprise them with his teleportation and his ability to throw his spear. However, someone like Endeavor with his powerful fire quirk could also put up a good fight against Scorpion.
I think Naruto would be really interesting. His never - give - up attitude and his large array of jutsu would be very different from what the Mortal Kombat characters are used to. He could introduce the concept of chakra to them and his shadow clone jutsu could really throw them off in a fight.
Scorpion from Mortal Kombat could be a very interesting character in this crossover. His hellish powers and his quest for revenge could put him at odds with some of the Naruto characters. His battles with Naruto or Sasuke would be intense, especially with his ability to teleport and use his kunai chain.
Power - ups and new abilities are also common themes. Writers often come up with creative ways for the characters to gain new powers or enhance their existing ones. And of course, the theme of good vs. evil is always present, with different takes on who is truly good or evil in the Mortal Kombat universe. This can lead to some really interesting character dynamics and plot twists.
Scorpion's back story is really tragic. As I said before, his whole clan was wiped out, and he was turned into this undead avenger. He lost his family, his life, and his very humanity in a sense, and is now trapped in a cycle of revenge.