I wrote this mainly to talk about ADV as I see it right now. Over the last year I’ve seen it both become more rigid, as well as certain anti-meta picks like Heracross, Moltres become more popular than perhaps at any other time.
To understand my perspective on the tier, it’s necessary to both note I’ve been playing for around a year by this point so most of my opinion is colored by post rest-talk mech changes ADV as opposed to before it.
A lot has changed, ADV feels very offensive right now to me, and the prominence of spikes exacerbates that. I feel like in spite of being quite old, a lot of team that did stuff like rely heavily on Rest Snorlax/Rest Suicune are becoming more and more unviable and difficult to get going without focusing an entire build and an almost mandatory support cast around them.
Defensive Suicune ironically can't be used as a bulky water at all,it is the one water that little support to the team in terms of switching into like CB Meteor Mash or CB Rock Slides from Gross/Tar; the best teams for defensive Suicune are probably Magneton+Claydol(possibly even wants Dugtrio+Rain Dance) teams, if only because even 1 layer of spikes with Sand down, means more likely than not Suicune will just be Resting all game; it's like Snorlax in that it is really spikes vulnerable, and hard to get going under sand. There's a reason why most teams still opt for Swampert(one of the best pivots in the game), instead of the more dangerous(on paper) Suicune.

Even teams that on paper have no real Rest CM Cune check, can beat it via rest looping, with stuff like CB Aerodactyl coming in on the rest turn under sand.If you have to talk of the most effective Suicune set, to me its probably still just offensive CM; but that set is prone to getting Toxic traded on it via Swampert/Skarmory/etc. Set with the most potential upside as stated above is defenitely SubCM, that set under sand though probably has only one good chance to sweep per game, although versus teams that have stuff that it abuses like Leech Celebi or IB+Fire Blast+Toxic Blissey it has chances to get very easy setup/sweeps. More traditional offensive Suicune sets, probably want stuff like Boom Regice/Boom Gengar+Dugtrio to create openings for it
Snorlax is kind of Suicune in that its most dangerous set, requires Magneton, and rapid spin support. Other sets like mixlax have steadily become less and less effective, Curse+Boom isn't as effective at trading with Skarmory as it used to be; my gripe with MixLax especially is that unless you catch Gengar on a switch with Shadow Ball, you're really just gonna get will-o-wisp'ed and basically be carrying dead weight. I also don't like how Zapdos under sand(especially if its not rest Zap), basically hurries MixLax into self-destructing much quicker than it'd like. Mixlax is usually thrown on to more physically oriented teams as a sponge but vs stuff like Zap/+1 Offensive Cune Hydro with sand, it really is just a whole slot dedicated to trading with boom.
In a tier centralized around spikes its only natural that controlling and abusing them became very central to how it operates. I've always thought that Gengar is the best pokemon at abusing spikes, . stuff like HP:Grass Gar becoming more popular has helped it counteract the trend of Pursuit Tyranitar being everywhere, while also letting it kill Swampert without having to eat Torrent Hydro Pump from higher ranges. Hypnosis is also amazing at cheesing teams right now, especially if you get the chance to use Hypnosis as Pursuit Tar comes in(even better with Spikes down) there are teams that you might just clean from that point on, which frankly is pretty ridiculous. Add to that the fact bulky gar takes a CB Aerodactyl Rock Slide(quite comfortably actually), and if running 252 HP/112 sp.def(Taunt+WoW with this is brutal) can switch out of a tyranitar's Pursuit in order to trap it with Dugtrio, and that only adds to the package. Gar with spikes down and Hypnosis or Taunt/WoW can also severely pressure Blissey(can just boom on it too I guess), great mon. The best thing about Gengar is that its stat spread is JUST good enough to both provide defensive utility as well as offensive presence
Skarmory is the best spiker, and a key defensive component as well on many teams; Skarmory between itself, bulky gengar and tyranitar can maintain hazards vs any team, and this is big reason why this is hands down the engine room of any TSS used in ADV atm. Want to mention that bulky mie without Magneton isn't very good at keeping hazards off, and that offensive mie is still the best set. The fact that it can spin on that(one time a game probably) is a bonus. Heck on certain teams(BKC's famous Cele Skarm Mag comes to mind) even WITH a magneton on the other side, you can potentially set up a situation to end up with three layers, which is kind of crazy frankly.
Tyranitar has evolved too, the flagship Taunt+Dragon Dance while still good is nowhere near as common as before, with mixed/special variants being the most popular which makes sense considering how Will-o-Wisp Gengar is always right around the corner. This is not to say that DD variants can’t be good: all of Taunt/Ice Beam/Toxic/HP:Grass have their place on it. Special Tyranitar+Forretress is quite a popular core, but I can’t help but mention that Forretress in a Gengar oriented metagame is quite possibly at its lowest. It still has value on double spiker outfits(which generally consist of Skarmory+Dugtrio+Forretress), but as the stand alone Spiker its much worse, which is definitely a fall from grace for the spiker on the metagame defining stall made by Tamahome many years ago(Tyranitar/Celebi/Swampert/Gengar/Blissey/Forretress).
Status spread also defines ADV at the moment so a number of Refresh users recently became much more popular in the form of Claydol and Milotic. Refresh Milotic especially can be frustrating to play against for teams relying on a low health bulky water to open up a chance for a potential DD Tyranitar or DD Salamence sweep. A lot of teams slowly but steadily lose to Toxic being spread amongst its members, and its only gotten worse because Heal Bell/Aromatherapy are very rarely seen on Celebi or Blissey right now. A popular strategy that’s emerged is using Magneton to remove Skarmory, to force bulky waters to accept Toxic.
When talking about spikes, its only fair to also mention how it should be taken on. There are a number of philosophies on tackling it, ranging from tacking on a Magneton, to running Magneton+a spinner, to running multiple Taunt users, to running teams with multiple flyers or levitators, to running spikes less offenses. But whatever you do, you need a plan to tackle them.
Ironically even though the tier is more offensive right now due to Gengar/Spikes, Heracross has emerged as a deadly counterpick and certain teams are 6-0’d by the popular SD/Focus Punch set, you’ll frequently see teams with configurations like Tyranitar/Skarmory/Swampert/x/Blissey/Gengar, that really have no practical outs in some cases depending on the x filler and the Gengar set. The rarity of Drill Peck on Skarmory makes this worse. Keeping proper switch patterns, and not falling into bad habits are crucial to succeed vs it.
Moltres has emerged as a solid B rank Pokemon, and an excellent filler for the 6th slot in TSS over the past year. It is an excellent way to abuse spikes and even running Blissey doesn’t necessarily mean that you’re secure versus it. When three layers are in play, Fire Blast is doing 25%, sand is up, and your opponent has physical options to double into versus Blissey you’ll often feel your options vs Moltres be choked off as you head into the end game.
Jirachi again has changed a lot, recently sets such as Toxic/Fire Punch/Wish/Protect and Fire Punch/Body Slam/Wish/Protect have emerged as excellent support with the first set being able to sit on Flygon and Swampert easily and force Toxic on to them, making late game Aerodactyl and Tyranitar far more dangerous. And the second sitting on most special attackers easily, both provide reliable Wish support which is great when Spikes are in play. Mixed Jirachi while not “new” in the sense that Toxic/Fire Punch is, is still vicious vs standard teams solely due to the coverage it has, while Superrachi(CM+3 attacks). Overall Jirachi has become much more notable than it was before, and is probably the best out of the CM trio of Suicune/Celebi and itself.
Swampert and Celebi are still key defensive pieces(while still possessing very good offensive sets in Endeavor Swampert, and offensive 3 attacks CM Celebi and SD/CM Baton Pass) but it has to be noted that they are very prone to giving up momentum and providing opportunity for spikes to be setup, so on more defensive teams it is not out of the place to see Magneton paired with them, Celebi being an especially good partner thanks to Baton Pass.
Metagross has also gotten a lot better over the past year, whether it be sets like Toxic(Toxic/EQ/Meteor Mash/Explosion or the notorious Toxic/Protect/Meteor Mash/EQ or Explosion) or Mixed Metagross and Choice Band Metagross. Mixed Metagross in particular with Psychic/HP:Fire is very anti-metagame and pries a lot of defensive teams open.
Even something traditionally defensive as Blissey has changed with Fire Blast/Ice Beam/Toxic/Softboiled emerging as the most popular set thanks to UD. This set is another way top players are adapting to spikes becoming more rampant. Calm Mind Blissey has fallen off quite a bit, which actually is a key reason for Substitute Suciune being in vogue again.
There’s always something changing,something shifting with respect to even a “static” generation like ADV. I’m looking forward to watching what changes SPL 2018 brings to the tier, and want to see the game being pushed forward more.
I hope to update this eventually as 2017 rolls into 2018.