Good god, I didn't think I'd have to defend Zygarde after most of us agreed it is an underrated threat. Let me just start with this: sorry
Uore , but Assault Vest Zygarde is kind of a dud idea; Zygarde does not have the raw (unboosted) power to do much with its boosted bulk, I mean it can take an Ice Beam so what....oh wait the most common Ice Beamer in the tier is Life Orb Protean Greninja which OHKOes 0 HP / 252 SpD Assault Vest Zygarde anyway (252 HP / 0 SpD takes more), and if you're telling me you're running more special bulk than that I can officially consider AV Zygarde as both a lackluster offensive threat and poor defensive response to almost anything due to its lack of recovery (it can't even Glare shit).
Edit: I forgot about Genesect and Deoxys-S, both of which
still 2HKO you with Ice Beam. How is Assault Vest Zygarde working for you again?
To put it nicely, Zygarde is simply outclassed to the other Dragon-types out there.
Let's see Zygarde for what it is: it is a Ground / Dragon. Are there any other Ground / Dragons? Yes, there is Garchomp and Flygon, but who uses Flygon (<-now
this is outclassed)? Garchomp has better offensive stats (well suited for Choice items), has Swords Dance and even a Mega Form, so that's several pluses for the land shark. But wait, Zygarde has Dragon Dance and Coil! We never had a
Ground-type that could Dragon Dance before, so that opens new doors for sweeping potential! Nor did we have a
Dragon-type that knows Coil, aka a Bulk Up that just happens to make its Stone Edge / Dragon Tail perfectly accurate, which again isn't something any other Dragon can replicate. And it even has
Glare + good bulk, which pretty much means parashuffler Dragonite just got overshadowed since Glare > Thunder Wave. Not 1, but
3 niches other Dragons (or Pokemon in general) cannot occupy, yet you say it is outclassed? Even if it's not the cream of the crop, Zygarde is still a very viable Dragon.
You should never use extremespeed on zygarde. A +2 adamant nature fails to even secure an OHKO on frail shit like greninja; that's just pathetic.
For the record, yes Dragonite is still the go to Dragon if you want an Extreme Speeding Dragon. However, it's not like it's completely useless on Zygarde, as it is still a useful move to have for priority, or against weakened opponents if Zygarde is unboosted.
DD is not the set for people to be running, Coil is. DD zygarde is certainly C+ material, but the sub-coil set pretty much bumps it back up.
I'm gonna reply to this with my "unquothed" quote.
Zygarde still has its advantages over both Dragonite and XZard, mainly its SR resistance and Ground STAB (plus Extreme Speed). Zygarde is a very viable option for teams who want a Dragon Dancer but aren't bothered to get rid of SR. For the record, DD Zygarde is not very weak at all: it may be weaker in comparison to Nite, but alternate STAB in Earthquake means it doesn't have to spam Outrage against any remotely bulky opponent it sees, and unlike XZard (if not running Roost) it has little to fear from priority. That, and the SubCoil set is the absolute tits to play against defensive teams since damn near nothing short of an Ice / Fairy move can break the Sub.
Zygarde definitely has its niches to fill: Dragon Dance Zygarde
arguably needs less maintenance than Dragonite to pose a threat to offensive teams, Coil sets can setup on weaker physical attackers, and SubCoil sets can make most defensive teams cry. And of course Glare sets can dick around with paralysis on everything bar Electrics and shuffle in unparalyzed foes with Dragon Tail. This is actually pretty damn versatile for a supposed 'outclassed' Dragon, whose only real flaw compared to its brethren is that it needs to boost to be an offensive threat, but the many ways it can do so is not to be underestimated. I still prefer to see it in
B+ for that matter.