Instead of talking about the drops themselves I thought I'd talk about some Pokemon affected by the changes.
Escavalier: This Pokemon has been getting a lot more use recently, even before the tier shift, and for good reason. It's one of the safest switch-ins to Alakazam, checks or counters Cresselia, Reuniclus, Mega Sceptile, Hydreigon, Salamence, Mega Beedrill, and many other dangerous pokemon, can break certain defensive cores with Swords Dance, and can Pursuit trap the aforementioned Psychic-types, Mega Sceptile, and Mega Beedrill to give things like NP Infernape, Cobalion, and friendly Mega Sceptile an easier time. This is all well and good, but the tier shift really gives Escavalier its chance to shine. It's one of the best switch-ins to Sylveon in the tier, and pairs fantastically with Sylveon's cleric set as well. It's a solid Celebi check, comfortably switching into all non-HP Fire variants. Zapdos's departure gives Escavalier teams more breathing room since they no longer have to worry about the tier's best Electric-type easily coming in for free. I expect to see Escavalier become a staple on bulky teams and cores.
Cobalion: Contrary to some opinions, I don't see this being better than in the pre-drop meta. While Zapdos leaving does give it a bit more room to run Stealth Rock or another utility move over Stone Edge (not to mention that Gyarados is still an important reason to run Stone Edge), that's one of the only changes that strongly benefits Cobalion. Celebi is a new check, although it is too early to tell if it will run the sets that deal with Cobalion the best (physdef and Life Orb Earth Power). Sylveon's entrance means Cobalion faces more competition as a Steel-type from Pokemon such as Escavalier that can more comfortably take on the Pixie thanks to higher special bulk and resisting Fairy. Although, one upside of that trend is that Cobalion is one of the best Escavalier counters, which means it is one of the best ways of breaking Escavalier/Sylveon cores, which will likely be very common. Overall the shift won't knock Cobalion down from its place as one of the best Pokemon in the tier, but it won't let it shine much more, either.
Hydreigon: On the one hand, it's pretty hard to say Hydreigon didn't get worse from this shift. The classic Taunt + Roost set now has to worry about letting a potentially Specs-wearing Sylveon in for free, mandating an even stronger Fairy resist as a teammate than before. On the other hand, Hydreigon has a lot of tools at its disposal to help it adapt to the changes. Life Orb mixed sets with Iron Tail or Specs sets with Flash Cannon might make a resurgence in order to not be Sylveon-bait while still being effective against teams without the Pixie, allowing it to keep its place as one of the scariest wallbreakers against balance. However, being forced to give up Taunt on a lot of teams significantly reduces its efficiency, as it no longer functions as a check to bulky Water-types nor can it have both recovery and a way to harrass all of its defensive checks on the same set. Conkeldurr is a new offensive check as well, although not one likely to have a great impact on the dragon's viability. Overall Hydreigon did get worse, but it is too soon to tell whether it lost enough ground to lose its spot as one of the top three Pokemon in the tier.
