Originally Posted by Fat IOS
There hasn't been any real standard at all in terms of rarity. Scraggy is currently top tier despite having a 5% encounter rate and a 50% shot of getting the right ability on top of that. Azurill has a 20% encounter rate in comparison. You'll be encountering it so often, you shouldn't have any problems finding a Huge Power one.
EDIT: You'll get into forced encounters with them too, since Repels aren't available at the ranch.
shed skin scrafty is actually useful if you don't want to stock on full restores, since hypers are way cheaper and still do the same shit