It's hard to say. Superman has incredible strength, speed, and heat vision. But Thor has the power of lightning and is a god. Hulk's brute strength is also a force to be reckoned with. In a fanfiction, it could depend on the situation and how the writer wants to portray their power levels.
I think Superman and Thor would be a very powerful pairing. Superman has his super strength, speed, flight, and heat vision, while Thor has his godly strength, control over lightning, and his enchanted hammer. Together, they could take on almost any foe. They could fly into space and deal with threats that are far away from Earth.
It's hard to say for sure, but Superman could be a top contender. His super strength, speed, and flight, along with his heat vision and other abilities, make him extremely powerful. He can withstand a lot of damage and dish it out just as well.
In my opinion, it could be Scarlet Witch. Her reality - warping powers are extremely potent. In a crossover, she could potentially change the very fabric of the combined universes. If she were to go rogue or be influenced by an evil force, she could cause chaos on a scale that would be very difficult for the combined might of the Justice League and the Avengers to handle. Even Superman's invulnerability might not protect him from her reality - warping abilities. She could simply make him mortal or take away his powers altogether.
It's hard to say for sure. Superman has incredible strength, speed, and heat vision. But Thor has his godly powers and the mighty Mjolnir. Maybe in a crossover, it would depend on the situation. If it's a fight in space, Superman might have an edge, but if it involves magic, Thor could be more powerful.
In such a fanfiction, there could be epic battles. The superpowers of both groups would clash. For example, Superman's strength against Thor's might. It would be a test of different ideologies too. The Avengers might be more about protecting Earth from all threats, while the Justice League has a broader view including intergalactic threats.
I think Thor and Wonder Woman would be really interesting. Thor is a god from Asgard with his hammer Mjolnir and control over lightning, while Wonder Woman is an Amazonian princess with her Lasso of Truth and super strength. Their different mythological backgrounds would make for some great exchanges and potential team - up action.
Wonder Woman could be among the most challenged too. She represents truth and justice in a very different way compared to the others. The Joker's chaotic and amoral nature could really test her beliefs. He might try to undermine her confidence in her own values and make her question the right way to dispense justice, which would be a difficult situation for her to handle.
I think Batman and Robin (from Young Justice) would be really interesting. Batman's brooding and strategic mind against Robin's youthful enthusiasm.
Definitely Thor and Aquaman. Thor is a god from Asgard and has his hammer Mjolnir, while Aquaman is the king of Atlantis and can communicate with sea creatures. They could have a really cool battle in the ocean, with Thor trying to use his lightning powers against Aquaman's trident and his control over the sea.
Captain America and Wonder Woman could potentially be rivals. Captain America has his strong sense of patriotism and old - fashioned values from the 1940s, while Wonder Woman comes from an ancient, mythical island with her own set of values. They might clash over different ideas of leadership and how to handle certain situations, like when to use force or diplomacy.