If I may, I'd like to point you to the GTS. When it comes to Ultra Beasts, people are quite willing to trade Buzzwole for Pheromosa; I'm sure you can look at those options.
And if I recall, there may be multiple Kartana in Sun while Moon has Celesteela. I'd be more than happy to give you one of those as soon as someone honors my trade thread in the future. X3