Basically any Pokemon with two normal abilities can benefit from this item. The main use of this item is to make it easier obtaining good Pokemon.
Let us assume you are IV breeding (a incredibly tedious task) a Scizor, and you have just gotten a near perfect specimen. Adamant Nature and perfect IVs, but it's ability is Swarm (anyone by their rigth mind wants Technican on Scizor). Instead of spending hours on breeding a new one, simply use the Ability Capsule, and you have yourself a perfect Scizor.
So there is no set Pokemon that benefit from this item, it's individually specific to almost every Pokemon if it's useful or not.