I have this memory a scene from the anime.
It was Ash (at least I think it was Ash) sleeping in a room with his pokeballs in a nightstand. One of those pokeballs turns out to be a Voltorb who bounces off Ash's head and hops away.
I remember this scene clearly because it gave me the idea that Voltorb could shrink down to resemble pokeballs.
But I checked out all of Voltorb's appearances in the anime and no such thing ever happened.
Is it from somewhere else or did I just fever dream the whole thing?