You are not alone. That was the only one I skipped so far. I know what to do: if they have no arms then they will jump toward you, and if they do have arms they will just keep walking, but I just don't have the patience to do it right. My reflexes always get the better of me and I press the wrong button before I realize they have no arms - and there's no room for error with those jumpers.
Don't remember where I stopped, though. The whole tower has been disappointing to me. Too much emphasis on challenges and not enough just plain fun. Even though I didn't skip it, the one I've hated the most is when Nightwolf only does damage with spirit weapons. I wasn't in the mood to learn his entire move set and figure out which attacks used a weapon, so it took me about a half hour to do it using only the two obvious special moves.
I heard that the difficulty tapers off the more times you fail, but with some challenges that just doesn't seem to me to be the case. The fact that Mileena and Baraka's back-to-back thing is random each time is what really made me give up on it.