Who would be the most interesting villain in an Arrow - Batman crossover fanfiction?

The Reverse Flash could be an exciting villain in a Supergirl Arrow crossover. His ability to move at super - speeds would make him a formidable opponent for Supergirl. He could also mess with Arrow's timeline, creating chaos in both their worlds. Imagine him going back in time to prevent Supergirl from arriving on Earth or changing events that led to Arrow becoming a vigilante. His manipulative nature and his connection to the Speed Force would bring a whole new level of complexity to the crossover story.

The Reverse - Flash would be really interesting. He could target both Batman and the Flash. For the Flash, he's a long - time nemesis, but for Batman, he'd be a new and extremely dangerous threat. His ability to manipulate the speed force and time could put Gotham in chaos in ways Batman has never seen before. And he could use his knowledge of the Flash to try and set traps for both heroes.

The Joker would be really interesting. Imagine Deadpool meeting the Joker. Deadpool would be both fascinated and repelled by the Joker's insanity. The Joker, on the other hand, would be intrigued by Deadpool's indestructibility and chaotic nature. It would create a really wild dynamic, with Batman caught in the middle trying to stop both of them from causing too much mayhem.

Ra's al Ghul would be a fascinating villain in a crossover. He has a global view of crime and destruction, and his Lazarus Pit gives him a certain immortality. His plans could involve both Hell's Kitchen and Gotham in some grand scheme. Daredevil would be out of his depth dealing with Ra's al Ghul's long - term, world - changing plans, and Batman would have to bring Daredevil up to speed while also trying to stop Ra's al Ghul's latest plot.

The Riddler could be very interesting. He could create complex riddles that not only test Batman's detective skills but also stump Spiderman. His maniacal love for puzzles could be a great contrast to the more straightforward villains that Spiderman usually faces.

The Joker would be really interesting. Imagine him getting his hands on some of Oscorp's dangerous technology. He could use it to create chaos in both Gotham and New York in ways that neither Batman nor Spiderman have seen before. His unpredictable nature would make it hard for the two heroes to anticipate his moves.

Darkseid is another option. His power and his desire to conquer Earth could bring Batman and Superman together. He could target both Metropolis and Gotham, and his presence would require the two heroes to combine their skills. Batman's strategic mind and Superman's brute strength would be needed to face this powerful foe.

Brainiac could also work well. He is an android with an insatiable thirst for knowledge and a penchant for collecting and destroying planets. In a crossover, he could target Earth, specifically Gotham and Metropolis. His advanced technology would pose a major challenge to both Superman and Batman. Superman's super - powers would be put to the test against Brainiac's powerful defenses, and Batman would need to use his wits to find a weakness in Brainiac's systems, leading to an exciting and complex story.

Reverse - Flash could be really interesting. He could manipulate time in ways that not only affect Flash but also Supergirl. For example, he could go back in time and prevent Supergirl from arriving on Earth, which would change the whole timeline. Flash would then have to convince her to come to Earth again while also dealing with Reverse - Flash.

Bowser and King Dedede teaming up would be really interesting. Bowser's brute strength and his ability to use fire combined with King Dedede's hammer - swinging skills and his own army of minions would pose a great threat to Mario and Kirby. They could be trying to take over both the Mushroom Kingdom and Dream Land for their own greedy purposes, like hoarding all the power - ups and food in both worlds.