That's why DC Comics invented Kryptonite. It's hard to create foes who can defeat an invincible being unless there are ways to make that being vincible. The fight, I think, is actually "believable" within the DC comics universe. They did a descent job of it.
One thing about this movie. I was a pretty harsh critic of Batfleck. I'm not all that much of a fan of Zack Snyder. I didn't see it in the theater, but I did buy it on blue ray. I didn't expect to like it, but it's actually not bad. It's not the quality of the Marvel movies, and the story isn't as well written, but it's worth seeing.
Batfleck could have carried the whole movie alone. I did like the recent Batman portrayal.
Stuperman... again, not so much. Same for BlunderWoman, could have been there or not, no difference to the final product.