So there is a lot of debate and back and forth about whether Batman could actually potentially create a suit that could stand up to Superman. After all, Tony Stark seemed to have done that with the Hulkbuster suit, right? Well, the fact is, he probably couldn't. At least not ordinarily... but if he had some help, that could change things...
Let me quickly pause here to say that I'm perhaps the biggest Superman fan ever. I LOVE the Man of Steel. I grew up watching Christopher Reeve (still one of my heroes) in the movies from the '70s and '80s and love the character and everything he stands for. I also think he's potentially overpowered, being the most powerful hero ever created (yes, even more powerful than the Hulk... but that's a debate for another day).
So when Batman fanboys pull the "preparation" or the "combat training" card, I tend to yawn. The comics have proven time and time again that, aside from magical items (like Wonder Woman's sword), only items from the planet Krypton (including krpytonite) can hurt Superman. Basically, nothing from the planet Earth will give Superman anything to think twice about.
But what if Batman's suit of armor is not entirely from Earth? Enter my theory:
Batman's suit is actually Zod's from Man of Steel
In Man of Steel, during the epic battle between Zod and Kal El that levels most of Metropolis, we see Zod discard his Kryptonian armor to fight Superman, potentially because he would feel less encumbered. Now that always stood out in my mind. Maybe I'm weird, but let's look at Zod's Kryptonian armor from the first movie:
Notice the pattern of the armor, the lines and the patterns. Now let's look at Batman's armor from the Batman vs Superman promo images:
Now it's obviously not EXACTLY the same, but if it's been modified to fit a human and augment his strength while giving him protection, it would probably change at least a little. Look at the lines and the patterns. They look very similar.
Let's look at another image, this time of one of the statues that is being created for the movie:
This looks a little closer, since the light is better on it.
My theory is that Lex Luthor is egging on this whole battle between the two heroes, and as part of that instigation, he's collected Zod's suit (as well as his body) from the ruins of Metropolis and has offered the suit to Batman to help him fight the Man of Steel.
Again, to those who doubt, I fully welcome the discussion. This has NO BASIS in any statements made by anyone connected to the movie. Simply a fan theory.