A quote about Contessa just to give an idea of how her ability works in combat, especially in regards to "getting hit" and what exactly "0%" means.
If he punches, her power supplies and puts her on track to avoid the punch unless you're saying that it's 100% impossible for a fit human to avoid the punch, 100% impossible for Batman to miss that punch.
Even if he does hit, if there's any possibility, however infinitesimally slim, that she could move in the right way and dampen/negate the blow, exacerbate a weeks-old injury on Batman's part, have him hit her in a way that damages his hand, leaves him momentarily slower as he shifts position to follow up... if there's any chance she could fool him, let the punch land but stay conscious and functional (or functional enough to see the rest of the steps through), and make that one of several steps to deliver the decisive blow and come out ahead, then she has it, and she takes the advantage (and wins) or skips straight to winning.
And in the midst of all of that, if she can move in a way that makes her momentarily - given the light - resemble his mother, or find any infinitesimally small crack in his psychology, that's free for her to utilize. Batman's careful attention to environment and detail becomes a liability as her power latches on to the fact that Batman is apparently a speedster and her best avenue to victory is to exploit his psychology. That thrown batarang at the outset gives her a window to move or make events conspire to make him think of a dead Robin, which buys her the necessary hundredth of a second of hesitation a few steps down the line.
She's limited by the speed of human thought (though to a lesser degree than a lot of people in this thread seem to think), but her power isn't, and can calculate vastly faster and more comprehensively than even Batman. When he's starting the fight, actually operating by the limits of a(n exceptional) human brain, her power is already 100 steps ahead at checkmate. It's not a question of 'if she's moving to react, he's moving to adjust to that reaction' - his adjustment was already called for and planned for.
Relevant bits are in bold and underlined.