To me,

may be the most broken Pokemon right now.
I will preface this by saying that I don’t necessarily think it’s necessarily the most pressing with the ongoing Gliscor suspect and the larger Gholdengo discussion, but it’s absolutely near the top of my radar.
Dire Claw aside, Swords Dance variants have their pick of checks and counters besides a few exceptions. Tera Ghost with Shadow Claw can take out Gholdengo, wall IDef BP Roost Uturn Corv, obstruct Zamazenta, surprise Skeledirge, and handle Dragapult all while neutralizing moves like Hurricane, Future Sight, and Earthquake that now turn into 2HKOs, which is all you really need. Tera Flying suffers from a little coverage issue as you still want Shadow Claw for Ghold, but a Poison move can come in handy. That aside though, coverage is similarly effective universally with very few misses and Flying Acro doing a ton of damage to neutral targets. Even Tera Dark or Tera Fighting with Shadow Claw and Gunk Shot can come in hand.
Dire Claw is another subtopic within the presence of Senasler as both in general and on some SD variants it can potentially make games unreasonable with not much counterplay, and this would be amplified if Gliscor were to get banned. I think many people point at it and say ban the move to keep Sneasler, but realistically Dire Claw isn’t even all of the issue or close to it. It is an issue that just makes the ongoing threat of Tera SD Sneasler with Terrain even more worrisome (and it validates pivot sets, but I don’t find them to be nearly as problematic).
Some people note that Rillaboom can be seen as a major culprit here as it enables some of the arguably broken strategies like this that we see right now, and to this I say I don’t really agree at the moment, but I get the relationship and if we had more time before DLC2 it’d be at least worthy of a discussion.
I personally plan on giving Sneasler a 5 (or maybe at least a 4) on the next survey if we have another before DLC2, which is still up in the air. Definitely think people figured out the best settings for this Pokemon and are now abusing it better than ever.