Don't forget Nature Power is not selected by Sleep Talk which is defaulted to Tri Attack in Pokémon Showdown and Psychic under Psychic Terrain.
This can make a Deoxys-A or S, as well as a Mewtwo-Y or X able to hit say Mega-Gengar, etc. for the KO if needed. I included Mewtwo-X because it uses Circle Throw, which Mega-Gengar is immune to. Sticky Web can ensure it hits with a STAB Terrain boosted Psychic first.
It also might be useful to include Flynium Z when carrying Mirror Move and Dragon Tail or Circle Throw.
Say you have a Comatose Mega Mewtwo-X with Sleep Talk, Circle Throw, Mirror Move, Nature Power / Copycat.
It switches in on Primal Groudon after your teammate has fallen to its STAB Ground moves. Being highly defensive, the Groudon doesn't predict you will Z-Mirror Move its own Ground move back at it, and gain +2 attack, KOing it in the process! The next turn they will wonder what ability you have and not realize you have a Comatose Pokémon.
Under Sticky Web and Psychic Surge / Terrain support, Nature Power can also allow Mewtwo-X to KO Pheremosa, etc.
Don't forget Skill Swap and Entrainment can stop the strategy. Having a Mega-Gengar with Entrainment Normalize supported by Sticky Web means the Comatose user has to be both faster than Timid Mega Gengar and carrying a Choice Scarf.
Also Protect/King's Shield + Speed Boost users can counter Comatose users. (If you will include Suction Cups, which is much less useful, Speed Boost doesn't seem out of the question). This is true due to the Baton Pass Clause, and because, unlike Contrary it doesn't require or limit the user to specific moves, and reduces the need for both Choice Scarf and Prankster especially for Taunt or Substitute.
So a Speed Booster whom outspends a foe after a Protect, or negates the Sticky Web speed reduction after a Protect, can outspeed the foe. Remember Protect doesn't just guarantee a Speed Boost, it stalls out a turn of Psychic Terrain.
A fast Speed Booster with a turn to stall is probably the best check besides Magic Bounce/Magic Guard/Regenerator Mimikyu.
Also, unless the Comatose user is a Dark type like Greninja, setting a different terrain down like Electric Surge or Grassy Surge can remove Psychic Terrain and allow for Priority moves, either forcing a switch or letting say Life Orb Grassy Surge Kartana use Bullet Punch.
Also, don't forget Unburden!
Simply using a Terrain activated Seed item (you switch in while a Terrain is up and get a stat boost), either during Psychic Surge on the foes team or your own Terrain like a Grassy Surge and suddenly your speed is doubled!
Using Recycle can also allow you to reuse Unburden.
For example Grassy Surge Kartana with Unburden and the Grassy Seed item. Now it boosts its Grass STAB, improves its Defense stat, heals 6.25% each turn, and Doubles its Speed. This also means instead of carrying Bullet Punch it can just use Power Whip, Sunsteel Strike, etc.
Lastly, ** what about Faster Mold Break users? Can't a Deoxys-Speed use Nuzzle on a Comatose PHazer if Mold Breaker bypasses the status immunity?
Lastly, Sleep Talk + Imprison on a faster or Prankster user is a sure fire counter. Imprison targets the user, not the foe, so it can work on Dark Types like Ash-Greninja, unlike Taunt-which is stopped.
Chansey @ Eviolite
Sleep Talk / Spore / Taunt
Whirlwind / Block / Taunt Chanseys.
Could you imagine if Chansey used Imprison as a Comatose user switches in, and then used Transform the next turn? Outspeeding and out walling the other team?
Initially: Transform, Whirlwind, Substitute/ Spore, Wish/ King's Shield was a move set used for Imposter Chansey in case the foe was imposter proof (such as using Parting Shot to switch into Chansey as the faster foe used Substitute). Eventually when people began using Imprison, or just because of the Ability clause, Prankster became an ability implemented for setting up before transforming, and allowing Imprison + Transform + Spore + Recover/ Trap move sets to come to fruition.
These are an alternative for the Imposter Chanseys, in case the foe had a Substitute, Whirlwind would be used to bring another foe in, more common last gen.
Aside from the headache-inducing font, I also have some other areas of disagreement with this post.
As pointed out earlier, Skill Swap + Entrainment doesn't work, and even if it did, it's an unreliable strategy because Sticky Web is not always guaranteed, has little use otherwise, and doesn't stop Mega Ray.
Protect / King's Shield no longer protect against non-damaging phazing moves, and therefore cannot be used to stop entry hazards + Whirlwind comaphase. That said, Speed Boost is also a questionably viable ability in and of itself, as there are few users of the ability that can really take advantage of it, otherwise. Also, Speed Boost doesn't even stop most comaphasers anyway, as the most viable users of it are usually slow, tanky Pokemon like the Primals that won't be able to outspeed even the slowest common user of Comaphase, Mega Ray, after +1. So, a fast Speed Booster with a turn to stall is actually a horrible way to beat Comaphase.
Changing the terrain works, but remember that terrains besides Psychic so far have been questionably viable. Grassy Surge Kartana is one way, but LO is definitely not its best item, nor will Bullet Punch do nearly enough damage to any of the best Comaphasers in the meta.
Unburden is awful as well. Seed + Unburden + Terrain is already a multi-step, multi-Pokemon process that has absolutely no use otherwise and that is completely outclassed by other simple boosting sets (for instance, Psychic Seed + Unburden + Terrain is already outclassed by Simple Quiver Dance or Z-Conversion in terms of bulk, Speed, and power). For a soft check answer to Comaphase, you have to sacrifice two abilities, an item, and multiple moveslots as well, as you have to guarantee that your Unburden user will be able to OHKO the Comaphase user, which is not easy.
Also, Unburden is single-use and otherwise impossible to get up before you get phased out unless you run something gimmicky to the level of Unburden + Terrain. Because it is single-use, Unburden + Seed + Terrain will also be severely restricted (as if it weren't already so because of how outclassed it is) because you'll have to hold off on taking advantage of the strategy until the Comaphase user is taken down, OR run Recycle, which is again unreliable because you won't possibly be able to Recycle in time once the phasing starts.
Your Kartana set is cute, but you can't have Grassy Surge and Unburden at the same time. You could run Grassy Surge on another Pokemon, but do you really want to devote a third of your team to a strategy walled by every major physical wall in the game? Grassy Surge itself is bad because 1. Grass is bad offensively 2. Grass-types are bad all-around 3. Passive healing helps both players so there is no net benefit, and it could even be argued that you suffer more as bulky walls gain more healing to help them stall you out.
I'm not sure if Mold Breaker lets you status Comatose Pokemon. Intuitively by the way Comatose is worded, I'm inclined to guess that it doesn't, but that needs to be tested. Either way, Nuzzle is not an answer either as it only halves Speed. You also have to be faster; not even Deoxys-S can outspeed any of the common Choice Scarf Comaphasers. And, even with Nuzzle, you have to wait until one of your faster, threatening Pokemon are shuffled in, which could take a while depending on your luck.
Sleep Talk + Imprison on Prankster is an ok answer.
But it doesn't work against Dark-types.
(It does, sorry) And you sacrifice two otherwise useless moves on Pokemon that are already traditionally limited by 4MSS. With Transform it seems interesting, however, though keep in mind that there will be no "counterphasing" as you are limited to only 5 PP, and also keep in mind that this is only a check because the only thing you do is force them out. Stil, this is probably the best answer you've posted, as it actually has acceptable use elsewhere.
But yeah the main point is, it's a lot harder to beat Comaphase than it looks, simply because it is such a high-reward, low-risk strategy that puts an extra burden on teams to prepare for it with things that are fairly useless otherwise. That is what makes it bannable.