I don’t direct pokemon anime nor am I in charge, but if I was, I would always have be wobbuffet vibrate and shake in response to environmental stimuli, such as when they move around, like a punching bag on a stand.
The only time they stop vibrating is when they are hit with an attack while using counter or mirror coat. They go eeriely still, as if they had been paused in a video, and then suddenly they unpause with all that built up energy and WHACK!
This would work best in 3d as 2d might be too hard to animate, I’d just have wobbuffet act like jelly until they counterattack.
While it's a standard idle animation, I'd argue its current animation does kind of make it look like it's swinging back and forth a little like a punching bag