With Zygarde and Kyub gone, it seems like this will be the big 3 ruling the tier: 
These are, in my opinion, the three deadliest offensive mons in the tier, and are all capable of completely shredding teams.
Pheromosa's ridiculous offensive stats and large movepool make it one of OU's most versetile threats. Somewhat similar to Genesect, Peromosa has multiple good sets, making it very diffiult to predict. It has base 137 attack and special attack as well as good physical and special attacks, meaning it can run a variety of good sets including band, specs and quiver dance. Figuring out how to counter it can be a matter of guessing which set it's running. It has great stab moves such as bug buzz, close combat, high jump kick, focus blast and lunge, and cover moves such ice beam, tripel axel, poison jab, throat chop, drill run and even fucking OUTRAGE! Beast boost does wonders for this thing, allowing it to snowball as it piles up kills. Its base 151 speed makes it the second fastest thing in the tier. Although it has frail defenses, it's very hard to kill because you simply can't touch it. Its quiver dance set is volcarona on crack, in many situations allowing it to set up QD virtually guarantees a loss.
Urshifu was at the top of the dlc1 meta and if that meta lasted longer it would have likely been suspect tested. Although the influx of new pokemon in dlc2 caused it to drop in usage for a little while, it's climbed back to the top of the tier and remains a major threat. Part of this is due to wicked blow. It's absurd to think about how powerful a bp 80 stab move that is guaranteed to crit is. Pokemon that usually resist dark are hit for close to neutral damage, pokemon that are neutral are hit to close to super effective damage and pokemon that are weak to dark are essentially ohko'd. This is one of the best attacks in the game. It also has great fighting stab in close combat and drain punch, and if its base 97 speed can't get it done, it has stab priority in sucker punch. Fairies seem to be the best check for this thing, but then you remember it has poison jab and iron head for coverage. This is all backed up by a formidable base 130 attack. Unseen fist is a fantastic ability, allowing the bear to punch right through protect. As for set, bulk up makes it a very strong set up sweeper, while banded wicked blow hits like a truck.
Spectrier has had an interesting journey in its short time in the meta. When its stats were first leaked, it was labeled as broken, then people laughed at its limited move pool. People soon figured out that with its raw power, its move pool is more than enough to shred most teams. Spectrier is arguably the best there is at flipping the momentum of the game on its head. The special attack boosts from grim neigh cause it to snowball very easily and 1 kill from this thing can quickly turn into 6. It's a fantastic scarfer, with base 130 speed that allows this set to come into battle a fire off shadow balls at anything that isn't a normal or dark type. It's sub hex set is more methodical but equally capable of fucking shit up. Hide behind a sub, set up with nasty plot, burn it with wisp then hex it to death. While it takes longer to set up, this set is even harder for the opponent to manage. You can also switch one of these moves out for disable, which can cripple would be checks. Saying that this thing gets walled by normal and dark types would be beating a dead horse (nice), but you can pair it with a good fighting type to take out its checks, then proceed to wreck everything else. The only other thing that can stop it is sucker punch. Also, it's massive base 145 SpA is the highest in OU. Thanks Gamefreak.
While I wouldn't go so far to call for a quickban on these three, they should definitely be on the radar for suspect tests once the metagame settles. Honorable mentions go to
and 
These are, in my opinion, the three deadliest offensive mons in the tier, and are all capable of completely shredding teams.
Pheromosa's ridiculous offensive stats and large movepool make it one of OU's most versetile threats. Somewhat similar to Genesect, Peromosa has multiple good sets, making it very diffiult to predict. It has base 137 attack and special attack as well as good physical and special attacks, meaning it can run a variety of good sets including band, specs and quiver dance. Figuring out how to counter it can be a matter of guessing which set it's running. It has great stab moves such as bug buzz, close combat, high jump kick, focus blast and lunge, and cover moves such ice beam, tripel axel, poison jab, throat chop, drill run and even fucking OUTRAGE! Beast boost does wonders for this thing, allowing it to snowball as it piles up kills. Its base 151 speed makes it the second fastest thing in the tier. Although it has frail defenses, it's very hard to kill because you simply can't touch it. Its quiver dance set is volcarona on crack, in many situations allowing it to set up QD virtually guarantees a loss. Urshifu was at the top of the dlc1 meta and if that meta lasted longer it would have likely been suspect tested. Although the influx of new pokemon in dlc2 caused it to drop in usage for a little while, it's climbed back to the top of the tier and remains a major threat. Part of this is due to wicked blow. It's absurd to think about how powerful a bp 80 stab move that is guaranteed to crit is. Pokemon that usually resist dark are hit for close to neutral damage, pokemon that are neutral are hit to close to super effective damage and pokemon that are weak to dark are essentially ohko'd. This is one of the best attacks in the game. It also has great fighting stab in close combat and drain punch, and if its base 97 speed can't get it done, it has stab priority in sucker punch. Fairies seem to be the best check for this thing, but then you remember it has poison jab and iron head for coverage. This is all backed up by a formidable base 130 attack. Unseen fist is a fantastic ability, allowing the bear to punch right through protect. As for set, bulk up makes it a very strong set up sweeper, while banded wicked blow hits like a truck. Spectrier has had an interesting journey in its short time in the meta. When its stats were first leaked, it was labeled as broken, then people laughed at its limited move pool. People soon figured out that with its raw power, its move pool is more than enough to shred most teams. Spectrier is arguably the best there is at flipping the momentum of the game on its head. The special attack boosts from grim neigh cause it to snowball very easily and 1 kill from this thing can quickly turn into 6. It's a fantastic scarfer, with base 130 speed that allows this set to come into battle a fire off shadow balls at anything that isn't a normal or dark type. It's sub hex set is more methodical but equally capable of fucking shit up. Hide behind a sub, set up with nasty plot, burn it with wisp then hex it to death. While it takes longer to set up, this set is even harder for the opponent to manage. You can also switch one of these moves out for disable, which can cripple would be checks. Saying that this thing gets walled by normal and dark types would be beating a dead horse (nice), but you can pair it with a good fighting type to take out its checks, then proceed to wreck everything else. The only other thing that can stop it is sucker punch. Also, it's massive base 145 SpA is the highest in OU. Thanks Gamefreak.While I wouldn't go so far to call for a quickban on these three, they should definitely be on the radar for suspect tests once the metagame settles. Honorable mentions go to
and 
