Zygarde?! Really?!!

You wanna know a Pokemon in my top three completely unfazed by list? Zygarde. Meanwhile got-something-for-everyone perfect coverage Kartana terrorizes teams that aren't prepared (using the same top 20 OU Pokemon). I mean come on, guys, I didn't even see this coming. That's how much Zygarde didn't matter. Maybe you guys could enlighten me?