After playing this metagame almost constantly for the past week, I have a pretty decent idea of some of the bigger threats here, so this is going to be a series of mini analyses that can hopefully help some people get into this metagame.
Offensive Threats:
Honchkrow
This guy can run Choice Band, Choice Scarf, Mixed or Physical All Out Life Orb, or Bulky Sub, and all of them are extremely strong. Even a Nasty Plot set is probably viable for shock value alone. My personal favorite is the Bulky Sub Krow, but personal preference is for a different discussion. This guy's Brave Birds are extremely strong, and you have to watch out for his Sucker Punches as well. The best stop to this is Eviolite Rhydon or Rhyperior, who laughs at the Brave Birds and doesn't care about Sucker Punch as he attempts to use Stone Edge. Superpower does decent damage as it is on a lot of Honchkrow's sets, but it's not even a 2hko on Rhyperior and DEFINITELY not on that Eviolite Rhydon. Honch usually isn't that bulky (unless its the sub set), so priority can do a number on it in the forms of Mach Punch from various mons in the meta. Honch is also quite slow so it can be revenge killed by most speedy things that aren't afraid of Sucker Punch, which makes Primeape an excellent revenge killer (but obviously you can't switch him into a Brave Bird). A good partner for Honchkrow on your own teams is definitely a rapid spinner, as Honch does not enjoy Life Orb damage + Stealth Rock damage + Brave Bird recoil, which can severely hamper his sweep. Claydol has decent synergy with Honchkrow, being immune to electric and resisting rock attacks. Claydol can also work to set up his own Stealth Rocks to hamper the opposing team.
The Quiver Dancers - Venomoth, Lilligant
These are the two most viable Quiver Dancers in the tier, but really anything with Quiver Dance can cause havoc (lol Butterfree). Both of these function mostly in the same way and both have merits to being used over the other. Regardless, Quiver Dance boosts speed, special attack, and special defense, and after one or two of these you really can't expect to be killing them with a special move. Furthermore, both of these Pokemon commonly run Sleep Powder to eliminate their counters (which there are not very many of). Venomoth has Tinted Lens which ignores resistances and makes its Bug Buzzes absurdly hard to stop, and Lilligant has Own Tempo Petal Dance or Giga Drain for either massive damage or recovery to help increase the longevity of their sweeps. They are both perfectly capable of running bulky RestTalk sets and all-out offensive sweeping sets, and both are extremely powerful in this metagame. The best way to stop the sweeping sets is to inflict them with a status (paralyze or burn, since Venomoth can't be toxiced) or hit them with a speedy scarf user before they accumulate multiple Quiver Dances. Scarf Typhlosion outspeeds Venomoth after +1, but I don't think he outspeeds max speed Lilligant (correct me if I'm wrong. Either way, Lilligant usually won't do too much to Typhlosion). Typhlosion can then attack with a strong super effective fire attack and decimate the dancers. The Rest Talking sets are much more difficult to stop, and you have to be on top of your game against them and knock them out before they start getting too powerful. You can weaken them so they use Rest and hope the Sleep Talk doesn't hit their attacking move while you try to pummel them with a Brave Bird or something, but that can be very risky at times. Basically you just can't let the RestTalking sets get set up. In the realm of walling these Pokemon, Eviolite Munchlax is a pretty sure bet, and he can phaze both out with Whirlwind. You only have to be wary of Sleep Powder. Moltres can sometimes wall them depending on the set, but if people catch on to my Lilligant set that uses HP Rock, Moltres will definitely not be walling anytime soon. Venomoth likes a Rapid Spinning partner since she has a Stealth Rock weakness, and Lilligant appreciates a lack of Toxic Spikes on the field since she is very susceptible to those.
Yanmega
Pretty much the biggest menace in the entire tier. He is capable of running two extremely powerful sets: a speed booster, and a SpecsLens set. Both sets are incredibly powerful, and if you don't have the right check/counter on your team, you WILL get swept. The Speed Boost set uses Protect to get a boost and then will be outspeeded by basically nothing, and Yanmega will be free to fire off Bug Buzzes and Air Slashes (and then a third move which is up in the air. Giga Drain is the best option, imo). Yanmega has a high special attack stat, so it's very hard to wall this guy. The SpecsLens set is, imo, more devastating. With Tinted Lens, nothing resists Yanmega's Bug Buzz, so it's nearly impossible to take. The best counter to both sets is Eviolite Munchlax, who can fire back a Rock Slide or simply phaze Yanmega out. Rotom-S is a good stopper of the Speed Boost set, but can't take the SpecsLens's Bug Buzzes. Electrode is immune to Bug Buzz, resists Air Slash, and fire back with super effective electric attacks, but can't take HP Ground if that's Yanmega's third coverage move. Specially Defensive Gastrodon can tank a few hits as long as Yanmega isn't running Giga Drain, but is not going to enjoy Specs boosted Bug Buzzes. Basically, the Speed Boost set has a few decent checks, but there really isn't any counter to the SpecsLens set. In terms of teammates for Yanmega, once again a spinner is appreciated, but most people run Yanmega in the lead position so the 4x Stealth Rocks weakness can't be exploited.
Sharpedo
Sharpedo is another Speed Booster that wreaks havoc in this tier, and is even more dangerous in the rain. The most threatening set is his Mixed set, with Surf/Crunch/Ice Beam/Protect, of which there aren't a ton of counters too. The best answer is Eviolite Ferroseed, who walls basically any Sharpedo set to death. Tangela doesn't have a problem either if Sharpedo doesn't have Ice Beam, but it often does have Ice Beam which poses a problem. Blastoise is a great tanking check, and can even burn Sharpedo with Scald to severely hamper its efficiency. Gastrodon is another excellent answer, as he is immune to water attacks and is bulky enough to take the other attacks Sharpedo can throw at him. Sharpedo is also weak to fighting priority, which makes Hitmonchan or anything else with Mach Punch a pretty good answer.
Durant
The best way to stop Durant is to just hit it with basically anything. Seriously, it is that frail. However, if you're facing a good Durant player that eliminates your priority users and scarf mons, you're in for some hurt, because Hone Claws Hustle Durant will slaughter basically anything in the tier. Iron Head/X Scissor/Stone Edge are its usual coverage moves, and are more than enough to decimate almost anything in sight. Eviolite Gligar is a great answer, as he can tank a hit and Roost of the damage with no problem, but he can't do a whole lot back, and if Durant tries to set up another Hone Claw or two, Gligar will be in serious trouble. Most Scarf Pokemon, like Scarf Typhlosion, will have no trouble KO'ing Durant, as Durant is incredibly frail.
Rhydon/Rhyperior
Rhydon and Rhyperior are serious heavy hitters in this tier. Earthquake and Stone Edge are the only coverage moves they really need to achieve excellent coverage. The common sets are Rock Polish, SubSD, or a simple tank that sets up Stealth Rock and Phazes (some sets might even try to use both Rock Polish AND Swords Dance. If that player manages to set this up on you...good luck. You'll need it). Every set Rhyperior uses is walled by Eviolite Ferroseed, Tangela, and Gligar (if you haven't noticed, it's good to run one of these three on your team). One of the best ways to take care of any Rhyperior set that's not the Rock Polish set is by simply using something faster than it (which is basically everything) that can exploit one of Rhyperior's 4x weaknesses (water and grass). Blastoise is a great tanking answer, while Sharpedo basically uses Rhyperior as set up fodder. The differences between Rhydon and Rhyperior are simply a matter of more defenses versus leftovers recovery. It's really the same issue as Blissey versus Eviolite Chansey. Players that plan on using one of these Pokemon as a utility Pokemon or a Rock Polisher should use Rhyperior, but the SubSD is probably more potent on Rhydon as he can tank almost any physical attack in existence, and most won't even break his sub.
Galvantula
Another bug type! (Noticing a pattern?) Galvantula's best set is his Choice Specs set, where he uses Compound Eyes to boost his accuracy so he can fire off Thunders all over the place. Some players use Expert Belt to give the allusion that he's holding Specs to take a player by surprise, so take that into account. Usually the coverage moves used are Thunder/Bug Buzz/Energy Ball/HP Fire, and these moves provide excellent coverage in this metagame. Once again, Munchlax is the premier special wall in the tier and can tank Galvantula's hits fairly well. If our electric spider is choiced, you can switch around to take resisted or immune hits, such as switching in Rhyperior on a Thunder. If you're putting Galvantula on your team, you want a spinner so you can keep bringing in your spider to fire off those Thunders since Galvantula is susceptible to every type of entry hazard.
Alakazam
A menace of destruction that almost no one uses (I used him to get up to top 20 on the ladder). The best set, in my opinion, is SubCm with Psychock and Focus Blast. With this, Alakazam can use his insane speed to set up a quick Sub and get fast Calm Minds in until he isn't even touched by Special Attackers. Psyshock is used over Psychic to make this a Cresselia killer; most Cresselia like to try and set up Calm Minds alongside you, thinking it's going to be a stalemate in the end. But then you surprise them by hitting them for over 50% with a +6 Psychock. Still, considering how common bug types are in this tier, Alakazam gets faced with some tough situations quite often. Things with strong priority like Choice Band Entei can knock Alakazam out of commission. Frankly, physical attackers that are faster than Alakazam in general are a bit of a problem. Yanmega hurts Alakazam bad after it gets some Speed Boosts and the ability to outspeed Zam.
Rain
This is very general, because there are multiple viable rain sweepers. Rain as a whole is very powerful and arguably broken in this tier. You will often see Electrode setting up an 8-turn monsoon of destruction where Shell Smash Omastars, Ludicolos, and Swords Dancing Kabutopses rip our face in half. There aren't many good answers to this besides trying to stall out the rain. Rain Dish Blastoise does well against everything but Ludicolo. Running a Rain Dish Ludicolo on your own team can help wall the sweepers. Pokemon with the Cloud Nine ability can help by getting rid of the rain (so Golduck and Lickilicky I think...nothing else <_<). Eviolite Ferroseed and Tangela wall the offensive rain sweepers but are in serious trouble if they face anything special. If you survive the initial rain onslaught, try to KO the Pokemon that set the rain up before they can get it off so you don't have to feel the pain again. Another decent answer to rain is Sharpedo, who can use your opponent's rain to fire off boosted Surfs, and can let Speed Boost accumulate until he's faster than the rain sweepers (Yanmega is in the same boat here to an extent, and can use Giga Drain and Bug Buzz to kill off Omastar, Kabutops, and Ludicolo).
I'll work on defensive threats later. And if there are more offensive stuff people think of...let me know.