Seeing as the Rachi ban is basically a foregone conclusion at this point I'd like to talk about potential bans or resuspects after DLC.
While I know it's generally frowned down upon to talk about the future I'd like to do so regardless, it seems that when there isn't someone saying what to do nothing is done so I plan to lay the groundwork.
This is the list of mon currently confirmed to be returning.
Section 1: Potential Unbans of Previously QB'd Mons Going Into DLC
It's been thrown around that certain mons should be retested from the pool of mons that were very quickly QB'd. The offenders in question being Melmetal, Kyurem-Black, and Marshadow. I'd like to go ever each one's chance of being allowed back in.
This shit may be fine after DLC, but I doubt this. It singlehandedly invalidates physical attackers and there's not really any good special attackers capable of beating Melmetal, at least currently. Maybe w/ DLC we get better special attackers and physical walls that are better suited to dealing w/ Melmetal but I can see it being a similar case to Mimi/Rachi where you were basically told "run exca" but this time w/ Volcorona. I really don't want to see time wasted on resuspecting this thing unless to power creep is insane and looking at the returning list there is a fair amount of new stall mons so maybe. Registeel, Volc, Zapdos, are def capable of beating Melmetal but I don't want another case of there being a pool of 5 mons checking one broken and making an incredibly unfun metagame (looking at you Mimi.)
This is the one I'm most unsure on as one mon completely invalidating every physical mon is no bueno but there may be a fair amount of returning mons that keep this in check.
I think this will absolutely be fine. I mean it think it's kinda fine rn but additional mons will firmly cement that this thing is fine. Sylv, Darm-G, Haxorous, Registeel, Crustle, Azu, Blissey/Chansey, Cress, the Tapus, and the various returning dragons (Latis, Garchomp) all force Kyu-B to run a bunch of sets at once to beat all of its counters and the sets' opportunity costs are pretty large (as opposed to a certain stupid ghost/fairy mon.) I feel the most strongly about freeing KyuB post-DLC out of the trio. Please quick free this thing when DLC drops.
I feel Marshadow would suffer from the same issue Zera is currently suffering from, no Z-Moves hurt this thing significantly. 125 attack isn't bad per say but it's pretty underwhelming especially w/ a 125 speed that kinda forces you to run a significant amount of speed. 90/80/90 bulk is a bit annoying and being unable to boost on Marshadow is a massive pain but I think it's worthwhile to look at this thing in a potential suspect test, hopefully sooner than later.
Section 2: Potential Unbans/Resuspects of Mons Banned From SS
As stated previously alongside bans, there has been discussion of resuspecting certain threats once DLC drops. This time, it's five different threats all of which were banned for being unhealthy to the meta. The question being, are these mons/mechanics still overbearing in a post DLC SS?
[Getting Big On 'Em] Dyna does not promote a healthy meta I never think it'll belong in 1v1 as it just turns the tier into coinflips. No new mon will suddenly make dynamax fine it makes an incredibly volatile meta that prefers winning 50/50s over making good picks or having good prep.
Encore/Disable+Prankster is an inherently broken combo the only scenario I can see it being fine is a significant powercreep. Looking at returning mons, it is nowhere near enough of a powercreep to justify freeing Sableye.
Imprison+Transform w/ 100s across the board in addition to an incredible movepool allowing for excellent choice sets to check usual counter forcing set guessing on preview in addition to 50/50s after picks. This thing will remain broken until there are way better mons that occupy 100+ speed tier. It's borderline acceptable post DLC but I really doubt it'll be fine unless Marshadow/Melmetal/Kyu-B are freed forcing the meta into a much more offensive meta (which personally I believe is way better than the stally mess that post-DLC currently looks like.) Honestly, I think it may be fine depending on how the meta pans out but if it's stall-centered like it looks to be Mew is not something that would a healthy presence.
Yeah w/ powercreep this thing will be nowhere near banworty. It has already been mentioned that this thing is planned for a resuspect post-DLC and I don't have any issues w/ that. Necrozoma struggles dealing w/ stall mons if its not Stored Power but that has a lot of opportunity cost so I doubt Necro will be anywhere near the menace it was pre-DLC.
Inherently broken ability. This thing should've never been considered as a healthy presence for the tier and going forward we shouldn't screw w/ it. It forces the meta to bend to Mimi and it makes such an incredibly unfun metagame. My biggest issue w/ Mimi is the complete lack of opportunity cost for adding things to its checklist. DLC could introduce 10 new checks for Mimi and within the week they would all become unreliable. Please never let it back in the tier, it does not belong when it contributes absolutely 0 to 1v1 and is instead a massive hassle in each part of the tier.
Another inherently broken mon. 100 speed w/ a 60% percent chance to just beat supposed counters. If you want longer reasoning on why this thing will absolutely never be fine look at the other posts in this thread.
Section 3: How I think tiering should be handled moving forward
While no one can predict how exactly DLC will turn out, I think it's a pretty fair assessment to say it looks stall-centered. There is a distinct lack of breakers while there are vile stall mons like Cosmic Power Cress, RegiSerp, Azu, Chansey/Blissey w/ Charm+SToss, Zapdos, and whatever else comes back. Our premier breaker being Volc is a scary prospect and honestly, I think it looks like Exca 2.0. There are definitely ways of alleviating these issues, this would be my way of going about it:
Keep mons with inherently broken mechanics out of the tier, mons that don't have inherently broken gimmicks should be looked at
Mew, Sableye, Jirachi, Mimikyu, and Dynamax should never be let in the tier again. Their gimmicks are each respectively unfair forcing unoptimal countermeasures (ie. Mew creating Copycat usage, Sableye forcing Dark types on each team, Mimi forcing you to run Multi-Hit moves) and on the other side of the coin you have mons w/ incredibly strong stats/typing but no one broken gimmick you could too. Yes, KyuB and Marshadow have incredibly strong base stats in addition to incredibly useful stab/movepools. However, I could run Sylv and beat both of those mons. No weird gimmick set and it's not a bad mon, on the contrary Sylv is quite good. I feel that plenty of viable mons check these strong mons while the gimmick mons force unoptimal gimmicks/mons. In a world w/o Rachi/Mimi you have no Excadrill. This much is apparent from the complete lack of Exca usage from gens 5-7. In world w/o KyuB or Marshadow, you still have plenty of Sylv usage, and other mons such as Hax, Dragapult, Zera, Gard, Incin, etc. still have plenty of usage and all are capable of keeping these mons in check. Yes, these mons will have to run slightly different variants w/ very little opportunity cost to dispatch KyuB/Marshadow.
TL;DR- Mew, Sableye, Jirachi, Mimikyu, and Dynamax should remain gone forever. KyuB, Marshadow, and Melmetal are worth looking at going into DLC. Inherently broken mechanics should not have to be worked around when it forces unoptimal techs, I see no issue w/ strong mons when all they do is encourage usage of mons that are already good. I know that the post is quite long, but I would appreciate if you read it. Peace.