Haven't seen many topics like this, pretty much just post a crossover you'd like to see and if you could explain how it could work or why, could be comic, videogames, manga, TV, or Movies. (I wasn't sure whether or not this would go in fanfic)
X vs Batman
I find this would be an interesting crossover because of the two characters both being great fighters, guardians of their cities, would go to great lengths to achieve their goals, and yet they have some large differences that would make a conflict between the 2 interesting, X uses firearms, is willing to kill and, has a law a rule of X that involves the execution of those whom break it, Batman on the other hand is against firearms, and refuses to kill that is his law not to kill.
How would this occur? Possibly Bruce Wayne is visiting Arcadia for business an associate of Wayne industries that lives in Arcadia has broken X's law and paid for a kill and tries to trick Bruce Wayne into providing money for him to get out. When Bruce arrives he could hear rumors about Acardia's guardian, but at first ignores it for superstition, but then starts to investigate when X attempts to take the Bruce's associates life. Bruce investigates as Batman later confronting X on the rooftops and ending the fight with batman falling through a window with a slash across his chest a warning and revealing that X knows Bruce and Batman are one. Batman then wants to learn more about X to know his enemy in a way. When the associate learned that Batman got involved he tries to get rid of Batman. The attack on Batman catches X's attention, and the two work together to take down a newly assembled (I'm unsure whether it should be Chaos Riders or Police Drones). In the end Batman was able to deduce X to be John Smith and after seeing what X has done first hand tries to use it as a bargaining chip to get out, X simply explains he that information was useless as a bargaining chip but lets him go because he understands his importance to gotham.
So what would you like to see as a crossover?