What it seems they've picked up on from MOS is to have Superman action really seem top notch, his threat level has to be raised to the point where the audience increasingly asks "how can he survive this?!"
Also multiple villains is never that hard of a thing to do. Nolan has already shown us that ten-fold. If you're a great writer, and if you do your research (many of the best comic titles use more than one villain), you'll see how it can easily be done to create an intense thrilling character piece summer blockbuster.
Possibly a henchman of some type.
Doomsday acting more as a weapon they utilize - think Kevin Smith's script just with Doomsday.
Go big or go home in the end.