Harley Quinn and Deadpool would be an extremely unexpected pair. Harley's chaotic and unpredictable nature combined with Deadpool's fourth - wall - breaking and equally chaotic personality would make for a really wild and hilarious fanfiction. They could get into all sorts of misadventures while trying to rob a bank or take on a super - villain just for the fun of it.
I think an unexpected pair would be Harley Quinn and Martian Manhunter. Harley's chaotic and unpredictable nature combined with Martian Manhunter's powerful and stoic presence could create some really interesting dynamics. Maybe Harley gets into some trouble on Mars and Martian Manhunter has to deal with her while also uncovering a bigger threat to the planet.
I think Batman and Black Widow would make a really interesting pair. Black Widow has her spy skills and combat training from the Red Room, and Batman has his own unique combat style and detective abilities. They could work together on a mission that involves international espionage and Gotham's underworld. Maybe they have to stop a group that is trading dangerous weapons between the two universes.
It's hard to say for sure, but many would argue that it could be Superman. His powers are almost limitless - super strength, flight, heat vision, etc. In a crossover, he would be a force to be reckoned with against most Marvel characters. However, characters like Thor with his godly powers and the ability to control lightning could also give Superman a run for his money.
It's hard to say for sure, but many would argue that it could be Superman. His super strength, speed, flight, and heat vision are incredibly powerful. He has been shown to be able to move planets in the DC universe. In a crossover, he could be a dominant force, but he also has weaknesses like kryptonite that could be exploited.
Gohan and Wonder Woman would be an interesting pair. Wonder Woman's combat skills and her connection to the gods could be a great match for Gohan's Saiyan powers. They could learn from each other's fighting styles and cultures.
I think Spider - Man and Harley Quinn could be a really interesting pair. Harley's chaotic nature and unpredictable behavior would mix well with Spider - Man's sense of responsibility. They could start off as unlikely allies, with Harley initially trying to play tricks on Spider - Man but then realizing they have a common enemy and working together in a really unique way.
I think Squidward from Nicktoons and Courage the Cowardly Dog from Cartoon Network would be quite unexpected. Squidward is always so grumpy and pessimistic, while Courage is, well, cowardly but also very kind - hearted. Their interactions would be really strange and comical.
Definitely Chat Noir and Iron Man. Iron Man's high - tech gadgets and Chat Noir's acrobatic skills and cat - like reflexes would make for a great combination. They are both a bit of a flirt too, so there would be some really fun banter between them while they're fighting side by side.
Hellboy and Wolverine would be a really interesting pair. Wolverine's feral nature and regenerative abilities combined with Hellboy's brute strength and demonic heritage would make for some great action scenes. They could have some really cool banter too, with Wolverine's gruff attitude and Hellboy's dry sense of humor.
One interesting pairing could be Godzilla and Hulk. Both are powerful, almost indestructible forces of nature. They could have an epic battle at first, as they both have a tendency to lash out when provoked. But then they could end up teaming up against a greater threat, like a powerful alien invasion. Another great pairing would be Godzilla and Iron Man. Iron Man could use his technology to study Godzilla, and perhaps even try to create some sort of armor inspired by Godzilla's abilities. And Godzilla could provide a physical presence that Iron Man could rely on in a fight. Also, Godzilla and Thor could be a fascinating pair. Thor's god - like powers and connection to nature could be paralleled with Godzilla's own primordial power. They might have a mutual respect for each other's strength.