2. The main villain has to be BADASS!
Before Matthew Vaughn left production, the largely rumored villain was going to be Apocalypse, which would have fit into the animated series storyline, and could be an interesting choice for the film. In the comics, the Sentinels were the main villains due to them wiping out almost all of the mutant population on earth. Now the Sentinels would work but it could be monotonous and would be like “The X-Men vs The Transformers” — awesome, but after you beat one…what else is there? Singer has always said his favorite villain is Proteus, and I am just hoping that they don’t put him into the film, he just wouldn’t fit. Then there’s Master Mold (essentially a Sentinel factory) which would be awesome, plus he COULD be added to the Apocalypse storyline and if done right, could have cataclysmic implications on the human/mutant/space/time scenario. And with Singer making usually longer than usual films, it needs to be a decently long film to fit EVERYTHING in it….but regardless of what they do…one thing MUST be in the film….