I hate to admit it, but I have used almost exclusively Sand offense and the Volt-Turn just cause it works so well. I use Scizor to check Terrakion cause it is a huge threat that cannot be left unchecked. And I kinda disagree with Terrakion having no true counters. Regenerator Slowbro counters it pretty well and isn't so niche that its useless against other things. Maybe this will sound crazy, but i think we may have been better off with the BW OU metagame if we had allowed Excadrill and Deoxys-S. Maybe if it gets too bad, could there be a possibility of doing like a trial with them allowed to see if it provides a more favorable metagame?