You might think that it's going to be a piece of cake to market this film, but Warner will be faced with the task of deciding whether to pitch it as simply a Batman vs. Superman showdown, or more a Justice League-type affair. The fact that it's sorta-but-not-totally-Justice-League complicates matters further, as with so many moving parts they may end up unsure about who to favour. I think the angle that makes the most sense is simply to market the film as a mammoth showdown between these two superheroes, in which fans will be invited to pick their side. To the casual cinemagoer, Wonder Woman is not going to be a deal-breaking draw for a film like this, but if they introduce her and possibly other JL characters in this film, then they can start an all-out marketing blitz for Justice League once the characters have been established here first. To me, that makes the most sense.