Source Screen Rant: Another bloke with a bit of time on his hands whipped up a fan trailer:

Like any trailer that tops out at 13 minutes it digresses often to various sub-scenes. In this one these scenes often entail characters making pointed statements and offer somber stares. The essential gist is that all these heroes are prepping to take on some big bad who turns out to be none other than Doctor Manhattan. Although some of the editing is pretty clever It doesn’t quite work visually as a whole, but admittedly it’s interesting to see these popular characters meshed together. Makes you realize how large a role superheroes have played in our TV and Movie consumption over the past two decades.

As for the battle advertised in the trailer?

My money’s on Doctor Manhattan.