What are some interesting ideas for superman crossover fanfiction?

One idea could be a battle between Goku and Superman to determine who is the strongest in the universe. They might start off as rivals but then realize they have more in common than they thought and team up against a greater threat like Darkseid and Frieza combined.

One idea could be that Superman arrives in the RWBY world and has to learn about Dust and its powers. He could team up with Team RWBY to fight a common enemy, like a powerful Grimm that is immune to normal attacks but not to Superman's strength. Another idea is that Ruby discovers she has some Kryptonian-like abilities and Superman helps her understand and control them.

One idea could be that Superman and Invincible have to team up to stop an alien invasion that threatens both their worlds. The two heroes could initially clash due to their different methods but then learn from each other.

One idea could be that an alternate - universe version of Superman comes to their world. This could lead to a power struggle as both Supermen have different ideas on how to protect the city. Another plot could involve Lois getting superpowers temporarily and having to learn how to use them while also dealing with her regular reporting job.

Here's an idea. There could be a powerful magical artifact that surfaces in both cities. It has the power to change reality. Superman, being a man of science, is initially skeptical about its power. Batman, on the other hand, has seen enough strange things in Gotham to know it's dangerous. They have to overcome their differences in beliefs as they race against time to stop different factions in both cities who want to use the artifact for their own gain. Along the way, they also learn more about each other's worlds and form a stronger bond.

One idea could be that Superman gets transported to the Marvel universe during a freak interdimensional event. He teams up with the Avengers to fight a common enemy like Thanos, who has somehow obtained Kryptonite. Their combined powers and different strategies would make for an epic battle and an interesting exploration of how the two universes' heroes interact.

One idea could be that Superman and Wonder Woman have to team up to stop an ancient alien threat that is immune to their individual powers. They must combine their strength, speed, and wisdom to find a way to defeat it.

One idea could be that a powerful new villain emerges who has the ability to manipulate both Batman and Superman's minds. This forces them to fight against each other while the real enemy is pulling the strings. Another could be a situation where Gotham and Metropolis are in a territorial dispute, and Batman and Superman initially take sides based on their cities, but then realize they've been played.

One plot idea could be Superman being transported to the Star Wars universe. He might use his powers to help the Rebel Alliance. For example, his super strength could be used to move large objects during battles or his heat vision to take out enemy ships. Another idea is that he teams up with Jedi. He could learn about the Force and they could combine their powers to fight the Sith.

One idea could be that Superman is somehow transported to the X - Men's universe. He teams up with the X - Men to fight a common enemy like a powerful mutant who has the ability to nullify Superman's powers on a large scale. They have to figure out how to combine their skills and powers to overcome this threat.