Re: Kotegaishi weakness?
We don't teach kotagaeshi, but a similar throw, koteoroshi, which is more straight up and down (it's thought to be safer for the wrist, I believe). Koteoroshi is my favorite throw to try to resist, because I feel like I have a handle on how much pain nage is going to cause me. In doing this we've found two things that help:
As several people have said, a lot of these throws work on unbalancing, and will still work even if nothing happens to uke's wrist. For munetsuki koteoroshi I hadve had the best results keeping my hands close to my center and stepping back slightly from uke so that he's stretched out. If you get into this position, the wrist lock is just icing; uke is already going down.
When you do need to move uke via his wrist and not just by unbalancing during the set-up, it helps to think of moving *your* body downward through uke's wrist, not moving uke's wrist. That is, get your hands in position and then instead of pushing down with your arm strength, keep your arms firm but relaxed and drop your whole body downwards. This is mysteriously hard to resist.