Agree/neutral with discussion slate except Starmie and Celebi going down.
Starmie is still exceptionally strong with Analytic, even stall teams don't actually have a good switch in except Blissey which is forced to always Heal after switching in a LO Psyshock. And it's speed tier is solidly above average while resisting a lot of priority making it an easy Pokemon to use on most offensive teams because of the utility this provides.
Celebi definitely shouldn't move down, especially being one of the best Breloom counters now. If anything, I would move it up because it can get around quite a few of the common Grass checks like Amoonguss and Crobat (on the switch at least) because of the Psychic typing. I still think Nasty Plot + Z Earth Power is the best set because only Blissey and Dragons are somewhat safe from it (and Kyurem, a rising Dragon in my opinion, can die to +2 Psychic with SR and always dies to +2 Z Earth Power with SR).
View attachment 101013
I think Decidueye should rise from C to B- or B because I think it's SD set is severely underrated right now.
Decidueye @ Decidium Z
Ability: Overgrow
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Swords Dance
- Sucker Punch
- Spirit Shackle
- Leaf Blade
First of all for the set, Sucker Punch can be replaced with Shadow Sneak which is more reliable but weaker and doesn't hit Pidgeot. But they are basically very similar.
This set is good because it combats defensive teams very well, as a physical Grass type its naturally threatening to the Alo/Quag/Blissey core. Unlike Breloom, Decidueye has a very reliable nuke in Sinister Arrow Raid which is a better offensive typing than Breloom's Bullet Punch - very few teams run Ghost immunities outside of Pidgeot and Blissey and especially at +2 Z Spirit Shackle is going to maul even resistances.
For example, in
this game Decidueye manages to find an easy time setting up on Swampert and lures in Muk - likely because my opponent is unfamiliar with Decidueye's power - OHKOing it with a +2 Sinister Arrow Raid (probably with a lucky roll to be sure). On the one hand Pidgeot seemed like a better switch in, on the other hand, this is only known is retrospect because 1) I could have U-Turned to rack up SR damage on Pidgeot 2) They values Pidgeot a lot because my team has no Flying resistances. I don't think the rest of the game deserves commentary because my opponent made some big mistakes, but early on, Decidueye already proved its worth.
And in
this game Decidueye also shows off its power, removing Klefki and giving me a large advantage after that because my opponent becomes very weak to Crobat. They unnecessarily give me a pretty much decisive advantage by giving up Gengar but Decidueye was already useful when killing Klefki. In fact, it may have been even more useful if it saved the Z move for Altaria because I could simply 2HKO Klefki with +2 Spirit Shackle.
Another important point in assessing Decidueye's viability is the fact it can beat or badly damage most Grass checks. For example, Sap Sipper Azumarill and Amoonguss are both easily OHKOd by a +2 Sinister Arrow Raid. Latias dies to +2 Sucker Punch most of the time even without SR. Crobat and Togekiss are fairly solid but both drop to a +0 Sinister Arrow Raid, Crobat not even needing SR.
The Ghost + Grass combination is resisted by only a few Pokemon, such as Hydreigon and Mega Houndoom (and Muk-A but that's not taking +2 Sinister Arrow raid well at all). Fortunately, Decidueye can easily find a partner with one of the best Pokemon in the tier because of this in Azumarill - every Azumarill set is a good partner and Azumarill benefits from Decidueye's ability to remove most Water types and even check opposing Grass types like Serperior and Breloom. Primarina also works because of the same typing.
Overall Decidueye's movepool and typing heavily compensate for its below average stat distribution because it can take advantage of several long brewing metagame trends - the power of stall, the overuse of Amoonguss, and the lack of Ghost resistances in UU. Because of this, Decidueye has been heavily underrated and should be understood now as a relevant, although not mainstream, threat.