Unfortunately, statistics are based off of ladder matches, and given that Doubles is still quite "new", our ladder comprises mostly of newer players. This will hopefully fix itself overtime, and I think it is since the ladder is much better than I remember (or maybe I'm just higher up idk)
When considering suspects, Sleep is definitely a good starting point (not as an option, as a starting point.) We can trust that we had a pretty stable metagame before we started considering Sleep Clause, or else we would have made other changed in the tier, and the only metagame difference between now and then is the lack of Sleep Clause, so anything that's broken SHOULD be improved by the lack of Sleep clause in some way.
The most direct pool of Pokemon in relation to the Sleep Clause removal are Sleep spammers themselves, but their typings and averagedly low stats prevent them from being broken. Many others, such as Amoonguss, have stepped up and taken a valuable role in the meta, checking other threats that could potentially be broken.
The next group on the list are our top-tier sweepers that benefit from the opportunity that Sleep spam causes. Pokemon such as Mega Charizard Y, Aegislash, and Mega Kangaskhan love being supported by Sleep, because they have so much more breathing room. There are some pretty darn powerful Pokemon in this group, so if we're gonna suspect something, it should fall under this category.
But which Pokemon specifically? An important thing to note is that each Pokemon benefits from sleep in different ways and levels. Keep in mind that many of the Pokemon in that group are pretty susceptible to Sleep themselves, so often the disadvantage outweighs the advantage. Other Pokemon simply don't benefit enough- either they can't capitalize upon the short opening quickly enough or they are burdened by counters that are not bothered by Sleep. This rules out a large portion, including the slow sweepers and sweepers that lack bulk / setup.
If you can tell what I'm getting at here, you'll begin to notice that I'm describing a lot of the traits of Mega Kangaskhan. It is a powerful threat benefitted by Sleep, but because of its bulk, speed, and power, Sleep comes at little disadvantage to it. It can set up easily with PuP, which also deals damage, and is almost impossible to prevent with Taunt, helping it quickly take advantage of even the smallest of windows of opportunity without fearing retribution. Its few checks and counters (Fighting-types, bulky walls) are all terribly discouraged by Sleep, which is often carried by Pokemon that naturally beat them (Amoonguss, for example, as Pocket stated, easily checks Fighting-types and can outlast most other walls in the meta. Jumpluff too has a speedy Sleep Powder and Leech Seed, which can even provide healing for Mega Kangaskhan if it switches in.) Mega Kangaskhan's traits are perfect for the abuse of Sleep, and abuse, it has- it benefitted so much from our last suspect, and could very well be broken now.
When considering suspects, Sleep is definitely a good starting point (not as an option, as a starting point.) We can trust that we had a pretty stable metagame before we started considering Sleep Clause, or else we would have made other changed in the tier, and the only metagame difference between now and then is the lack of Sleep Clause, so anything that's broken SHOULD be improved by the lack of Sleep clause in some way.
The most direct pool of Pokemon in relation to the Sleep Clause removal are Sleep spammers themselves, but their typings and averagedly low stats prevent them from being broken. Many others, such as Amoonguss, have stepped up and taken a valuable role in the meta, checking other threats that could potentially be broken.
The next group on the list are our top-tier sweepers that benefit from the opportunity that Sleep spam causes. Pokemon such as Mega Charizard Y, Aegislash, and Mega Kangaskhan love being supported by Sleep, because they have so much more breathing room. There are some pretty darn powerful Pokemon in this group, so if we're gonna suspect something, it should fall under this category.
But which Pokemon specifically? An important thing to note is that each Pokemon benefits from sleep in different ways and levels. Keep in mind that many of the Pokemon in that group are pretty susceptible to Sleep themselves, so often the disadvantage outweighs the advantage. Other Pokemon simply don't benefit enough- either they can't capitalize upon the short opening quickly enough or they are burdened by counters that are not bothered by Sleep. This rules out a large portion, including the slow sweepers and sweepers that lack bulk / setup.
If you can tell what I'm getting at here, you'll begin to notice that I'm describing a lot of the traits of Mega Kangaskhan. It is a powerful threat benefitted by Sleep, but because of its bulk, speed, and power, Sleep comes at little disadvantage to it. It can set up easily with PuP, which also deals damage, and is almost impossible to prevent with Taunt, helping it quickly take advantage of even the smallest of windows of opportunity without fearing retribution. Its few checks and counters (Fighting-types, bulky walls) are all terribly discouraged by Sleep, which is often carried by Pokemon that naturally beat them (Amoonguss, for example, as Pocket stated, easily checks Fighting-types and can outlast most other walls in the meta. Jumpluff too has a speedy Sleep Powder and Leech Seed, which can even provide healing for Mega Kangaskhan if it switches in.) Mega Kangaskhan's traits are perfect for the abuse of Sleep, and abuse, it has- it benefitted so much from our last suspect, and could very well be broken now.
