It's rather easy to exploit the forced use of Tera by the rest of Darkrai's team which is why i've never been a fan of this kind of argument, since it often puts the opponent in a lose of resources.
Before I touch on the next bit, I wanna address the offensive counterplay you listed before. Gambit/Dragonite is good, but it does struggle with Wisp variants as Darkrai being able to cripple both goes a long way to aiding its teammates to sweep later as they're threatened less by the burned prio users. Vacuum Wave Valiant... how many people are using that? Val already has crowded moveslots on every single set and I can't think of a reason you'd ever want it over the many better options. Rilla can only really revenge kill and Rilla actually does struggle a bit into certain Darkrai structures that tend to pack fat offensive resists to its grassy glide which makes it not as useful as you'd think. Banded Scizor is fine, if a bit hard to fit sometimes but it's a good answer I'll give you that. Specs Raging Bolt though... can't comment on how practical that actually is since I haven't seen it used in higher level play but I'm personally not a fan of it in concept because it's dependance on a priority move that fails if the opponen doesn't attack actually can be really exploitable, especially by protect users which are common on Balance.
For the record, I appreciate you bringing these examples. I think it's helpful and adds to discussion a lot. That said, I do have issues with some of them mainly because they're rather circumstantial answers. Obviously Kingambit may check Darkrai without Wisp/FB, or Dragonite/Gambit can help vs it without Wisp or FB+Ice Beam, but it's difficult to gleam what it's running from the outset of battle and potentially guessing wrong can give the Darkrai user a massive advantage. This goes for Zama and Tusk too which get ruined by wisp variants (and knock off cripples Zama). This is all disregarding the threat of Specs which has such immediate power that you'd want to respect its possibility quite highly. Switching in Zama expecting nasty plot only to eat a specs sludge bomb is nasty.
Now then, I don't disagree about Wellspring or Kyurem necessarily (Roaring Moon actually has fairly adequate counterplay right now between priority, chip and contact punishing, sticky barb clef and other strategies), the difference is that these pokemon aren't as volatile in their set possibilities which makes prepping for them more straightforward. I'd love to axe Kyurem too, and don't care for Wellspring, but I think But Darkrai's versatility and how punishing guessing the wrong set can be is, I believe, too much.
Not sure what Raging Bolt is listed for though. Undeniably great, but it's also honestly the most overhyped pokemon in terms of presence and impact. It rarely ever sweeps because it's something fairly straightforward to prep for and it's much more prone to chip due to its low speed and often being drawn in to defensively check things, which results in it being fairly easy to limit longterm. Again, great mon but I don't think it's anywhere remotely close to the big three balance breakers, let alone problematic.
Gliscor's great, no denying it, but there are match ups where the aggressive pace of some teams don't give it as many opportunities to be annoying and it especially dislikes the presence of Kyurem and Wellspring, the latter especially punishing SD sets pretty hard. Phys Def Glowking with Ice Beam can snipe Gliscor fairly safely as well, and Darkrai of course has that option as well. Gliscor also can't handle already boosted threats as easily, and without knock off it actually gives free turns to Balloon Gholdengo. it's important to identify what will give opposing Gliscor chances to come in so you can plan around these instances and sometimes, abuse them. Heck even Garg is annoying for non knock Gliscor since SR+Salt Cure means it's not geting any health back and boosting Garg can just beat Gliscor.
I totally get when a mon is frustrating though. No need to feel bad about a bias. I have my own. We all do! And debate like this is a lot more healthy and productive. So thanks for adding your input.
7th (17.6%) -> 6th (19.6%) - 11% jump in usage
11th (15.5%) -> 7th (18.7%) - 20% jump in usage
16th (12.7%) -> 9th (16.6%) - 30% jump in usage
15th (13.7%) -> 12th (15.5%) - 13% jump in usage
6th (18.7%) -> 13th (15.1%) - 19% drop in usage
12th (15.3%) -> 15th (12.9%) - 16% drop in usage
17th (12.6%) -> 19th (11.3%) - 11% drop in usage
23rd (8.7%) -> 21st (10.7%) - 24% jump in usage
25th (8.2%) -> 23rd (9.4%) - 16% jump in usage
30th (6.8%) -> 24th (8.0%) - 17% jump in usage
22nd (8.8%) -> 25th (7.8%) - 11% drop in usage
24th (8.4%) -> 29th (7.3%) - 14% drop in usage
32nd (6.2%) -> 36th (5.1%) - 17% drop in usage
42nd (3.9%) -> 39th (4.9%) - 24% jump in usage
35th (5.5%) -> 41st (4.4%) - 19% drop in usage
