I don't have much to add to discussion, 16+ days after the playtesting ended but... after using Aurumoth for a bit / reading through this thread, this entire CAP project has shown us (in my opinion) that Illusion is a ridiculously powerful on something that can take a hit. I'm not trying to say that Illusion was what "broke" Aurumoth, but rather that it can utilize that ability to its full potential (unlike Zoroark, the original Illusion user!) because it can take hits and set up easily (twice if its forced a switch and your opponent brings in the wrong pokemon). I ran Aurumoth on a HO team that focused on preventing SR and by forcing switches with Aurumoth by bluffing so I could set up. In one battle, I brought in Aurumoth disguised as a Terrakion, which made the opponent think "oh shit, better go into Gliscor"
Something to think about in the future if we ever decide to use Illusion again. It's an ability I want to revisit some day.