I wouldn't consider Amoonguss a volt turn counter, because of the reasons you mention concerning Scizor. Defensive Salamence makes me wince. I'm not comfortable with the idea of it, but I will admit you make a point. Zapdos is only the only perfectly hard volt turn counter in my opinion, and I think the specially defensive set is worth looking into for OU. Yeah when I read "salamence" at first I didn't think of a defensive set, which threw me off. It's because personally I run a hyper offensive moxie Salamence. Scizor won't stop that thing from sweeping usually, but I guess in a way I can't switch it into anything.