Okay, I made a similar post to this in the metagame thread, so I might copy some things exactly from there, but I feel like it's an appropriate time to make this nom. Long message incoming:
A+ ---> S
There are little to no drawbacks in using Greninja. Seriously. So first, let me just restate Greninja's exact influence in the meta:
First of all, protean. Can you even counter this thing? It has everything in its movepool - hydro pump, dark pulse, ice beam, hp fire, extrasensory, gunk shot, low kick, spikes (which are phenomenal rn), hell even grass knot iirc. Free stab on every move is huge.
Now I know newer mons like Koko, Pheromosa, and others can outspeed and revenge kill (whereas in ORAS it didn't face much competition as far as speed tier), but I still want to talk about why I think it's thriving just as much in SM as it was in ORAS. In ORAS, it mainly served as a cleaner - it had coverage for everything, Clef and Lati twins were everywhere, it could beat Ttar and even the Keldeo + Mega Venusaur builds, and its unpredictability factor was stellar. Now, it can serve two different roles: cleaning (for bulkier teams) or supporting a sweep (when paired up with things like Metagross, Mawile, or so on). Which leads to my next point:
A vast majority of teams are forced to run things like pex, ferro, steela, etc.. to try and counter the countless offensive threats present now. Teams need answers to Phero, MegaGross, MegaMaw, and so on.. and all these answers can be slammed by Greninja. Literally. Whether it's using these mons to break holes through the opponent's team to the point where ninja can just sweep, or using ninja to aid the sweep of something like mosa, volc, or whatever - there is literally no ninja set that you can't find to benefit your team (as far as I know and from my experience). Besides stall, which you can try and offensively overwhelm with popular partners like Lele + Mosa, there is no matchup where ninja is dead weight because it can adapt to anything. Greninja also benefits from mons like Heatran and A-Wak seeing a rise in usage (although A-Wak will probably drop in the future).
I also don't buy that it has 4MSS. Hell, Metagross also supposedly has 4MSS but look at that thing. Sure, you can scout its movepool based on the other mons and it is limited to only 4 moves, but this is easier said than done. Realistically, pivoting around and playing with its moveset will only mean that your team will become weaker and more vulnerable to other mons, especially with hazards. Nothing can defog/spin on this thing either.
Then there's the problem that from preview, you could also be dealing with specs ash-ninja, which is also ridiculously hard to counter. Ash-ninja's seen plenty of talk already and it goes without saying what it does. Specs hits everything hard, especially with darks and bulky fairies taking a major hit.
Now, I want to try and address the points that were made by the council when Greninja was dropped - realistically, I don't have the time to go sentence by sentence, but I'll try to hit the major points:
"It feels out of place with the other titans that reside in S rank that are basically centralizing the tier by themselves."
--> This in itself is a bit hard to judge. It's true that Metagross and Lando are on basically every team, but this isn't necessarily something that makes them 'better' than Greninja. Lando is a bit hard to compare due to their different roles, but is not extremely hard to wear down because it gets switched into a lot of attacks and is used to check opposing Lando as well. Metagross has a worst case of "4MSS" than Greninja, also gets worn down by hazards, gets switched into attacks much more often than greninja, and is also hurt with the increase of scarfers.
TL;DR - Greninja has superior versatility than Metagross and are dealt with similarly.
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"Greninja is a lot easier to pressure offensively this generation with the introduction of Pheromosa and Tapu Koko, as well as Choice Scarf users being on basically every team."
--> Although I know we can't talk about Pheromosa not influencing the tier anymore even though it's getting suspect tested, I'll just say that it being soon gone is amazing news for Greninja. Tapu Koko naturally outspeeds (and is hard to counter in general for a lot of teams) but it also not hard to wear down or revenge kill with scarfers, priority, or just outright using something like Tangrowth, which is on a ton of teams, to counter it. Not to mention a-ninja's shuriken already does a minimum 75% to it and has a chance to ohko after rocks, especially with Koko pivoting around. Scarfers are also not hard to take advantage of (bar Gengar, which has to rely on FB or dies to shuriken with chip as well), and there aren't a lot of scarfers which don't appreciate a water shuriken (IF it happens to be a-ninja and you were saving your scarfers up predicting protean). Things like Chomp, Lele (which rarely runs scarf anymore anyway), and Nihilego are easily switched into (Lele isn't 'easy' but steels are a problem). Scarf Keldeo has also risen in usage because of this (which again shows Greninja's impact on the tier, even though it's not the only reason for its rise), but is not hard to counter: Toxapex, Tapu Fini, Latios, Tangrowth, Clef, and Amoongus, and you will find at least one of these on every build. Not to mention that scarfers like Chomp, Gengar, and Keldeo also threaten the omnipotent MegaGross.
TL;DR - Faster revenge killers aren't hard to counter and take advantage due to the defensive backbones of builds nowadays.
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"..any well built balance or BO team should have answers to it defensively, and can rack up damage on it significantly between LO recoil and hazards. Celesteela, Ferrothorn, Mega Venu, Toxapex, AV Magearna, AV Magnezone.."
--> My favorite types of builds are BO, and it's much, much easier said than done to find answers for Greninja. All of the aforementioned mons are weak to two moves in HP Fire / Extrasensory. Celesteela and AV Magearna are two of the most reliable checks; AV Magearna is wittled down easily and has no reliable recovery, and is also trapped by the annoying Dugtrio. Celesteela is another victim of "Lando syndrome" in that its defensive typing makes it be switched into a lot of other moves. The rare flames max attack low kick 2hkoes it. Not to mention that Greninja only needs a little team support in the form of Zygarde/Duggy to already crap on all of these mons. A lot of people have the common misconception that Greninja is meant to handle all of these mons single-handedly, but with the right team support, it's not hard to break past them. The one major drawback which is hard to control is hazards wearing it down, but this applies to most offensive mons. However, if you're on the opposite side of hazards, it's extremely hard to deal with it considering NOTHING defogs/spins freely on Greninja (and if we're assuming Greninja's suffering from hazards, I don't see why you can't assume you've also set them up on the opposing side).
TL;DR - Greninja's coverage can easily bust past its checks, especially with the appropriate team support, meaning it doesn't have to carry all the weight.
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"..and depending on the opponent's team structure you honestly should be able to tell what coverage Gren is running.."
--> I deliberately left out the second half of this point since it was too long to copy/paste, but I think I've hit on this before. It's not easy to tell what coverage Greninja is running, and jumping to assumptions a lot of times can backfire heavily. The time you spend trying to decipher what coverage Greninja is running (assuming you're purely scouting) just means that your team is more susceptible to being swept by the partnered mons. Trying to tell what coverage it has from preview is also hard because if you didn't bring the right answers, then you're in for a hellstorm. Moreover, even if you do know what coverage it's running, your team is still taking chip damage assuming you even brought the right counters to the right set to begin with.
TL;DR - Greninja's coverage is too expansive to pack all the right answers to it on a single team, and trying to guess its coverage can make you lose to a bluff/other offensive partner.
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I know not a lot of people will take the time to read all of that, but I hope my points were made clear to the tiering council as to why Greninja is still as big of a threat as it was before and why it's deserving of S rank.
