Quash is one more that sounds vaguely familiar, but I'm not sure exactly what it does either. I know that I have never used it before.
I just looked it up to refresh my memory, and I'm still a bit confused. As I thought, it's non-damaging. It's goal is to make the opponent go last on the turn it is used, but it has no priority, so if your opponent moves before you then the move just fails--you can't use this move to slow down an opponent faster than you, it only works if the enemy moves after you...in which case you still wouldn't gain anything in a 1 on 1 trainer battle because you were already going to move first, and have just spent a turn not attacking when you could have done something. Unless there is a detail I am missing I can't figure out when this move would be good. Now if quash had priority to guarantee it struck first, and your opponent stayed under the effects of quash and got slow for some turns then I could see this move being threatening, but I don't think that's case.