On principle, I agree with you. I want coherence as well. But we gotta have some sort of consideration for the consequences that this would have on the metagame. No-one can predict those for certain, but from my and other opinions I have heard the metagame surely would not change for the better. To scratch the surface of the consequences: You gotta give Snorlax a reason to think twice before spamming Bodyslam at least. And Gengar is not the answer. It is a nice Pokemon to have once in a while vs Snorlax, but I think we can all agree that it is rather underwhelming most of the time, not to mention that it still does not deal with the combination of Chansey and Sorlax. The scouting of the Chansey moveset is an integral part of RBY, and one that adds some depth to the metagame. If Counter is banned, all that will be gone. It would be a significant loss for the matagame to see that go.Counter causes a bug? Counter should be banned.
Psywave, Fly and Dig never got patched, as much as i like Counter's role in the meta i'd like to keep the tiering at least somewhat coherent with itself, it's not like we can arbitrary decide that THIS move is too good for our ends to get the same treatment every other move had prior. If you want to go for the most enjoyable metagame and twist your own rules, fine by me, but then i want to have a good talk of 1/255 misses and other stuff as well following. Because you all know if it was any other move it was getting a quick ban and be done with it instead of this roundabout way to keep it where it is, coherence above all i say.
I too want to have a coherent solution, though. That is why I suggested modding Psywave in my previous post at the end as well. It is not consistent with the principle of being coherent if we mod Counter, but keep Psywave banned (no matter how unimportant that move is). Putting it in the same sentence as Fly and Dig is wrong in my opinion when it comes to modding them, though. I'll explain why:
We can group bugged moves into two groups. The first being moves that make the game unplayable (by causing desyncs), the second being moves that are bugged but the game remains playable (they do not cause desyncs). Counter and Psywave belong in the first group. Moves like Fly or Dig (and Hyper Beam or 256 misses if you wish) belong in the second group.
A simulator is not expected to preserve desyncs, I think we all agree on that. A sim gives us the freedom to take the moves from the first group and mod them (yes, Psywave got banned, but I fully agree that it should not be, and we should mod it!) The simulator is, however, expected to keep the specialties of the given generation intact (so long they do not make the game unplayable). We still ban certain things on our simulator or make clauses for them. These things include stuff that we deem necessary to keep the game competitive, but we generally keep them to a minimum. Hence there is a freeze clause, a sleep clause, OHKO moves are banned, we cannot bring pre-statused Pokemon into battles (which is possible in RBY) etc. Moves of the second category should be dealt with the same method: They do not make the game unplayable, but their bug might be broken in a competitive sense. That is exactly the case with fly and dig. It is coherent to ban those moves, instead of patching them by the logic I underlined.
Modding is the tool to deal with cases where moves make the game unplayable due to causing a desync. Banning (and clauses in extreme cases like freeze and sleep) is the tool to deal with things and moves that are broken in a competitive sense. Applying that policy would allow us to mod Counter while keeping moves whose bugs are broken (in the competitive sense, not in the "making the game unplayable" sense) banned. We must then unban Psywave, though, and mod this as well. Don't get me wrong, from a competitive sense, I could not care less if Fly and Dig got modded as well. But that, on the other hand, would indeed be incoherent.
Fine, that is reasonable. You are right, that a knowledgable player would only make that move on cart to make the game desync in case the opponent counters. It is not a valid counterplay in the spirit of the game. We should probably go with your version of Option 4 then. Just speaking from personal preference, the "being able to kill the switch-in with Counter" thing is something that rubs me the wrong way and I'd like to see it gone. But I agree that there is no logical path that could lead us there, so I gladly give in on that one.This seems like an overwrought solution to something that is not a problem. There is a trivial solution here, which is on cart battles you ban players from changing the selected move in the attack menu before switching. This is implemented by default on Showdown.
I get that we would be changing the mechanism of counter anyway, but the goal should be to keep things as similar to the cart as possible. Where there's an easy win we should stick with that.
There is no counter desync on that turn without that specific counterplay, and that specific counterplay is trivial to ban. Patching in that situation takes us further away from how the game would be played on the cart.
To justify your scenario we have to assume one of the players is intentionally trying to cause a desync, therefore the way the game is played between cart and showdown is suddenly very different. One player could be incentivised to use a move in the cart game (countering to cause a desync) that they would be incentivised to not use on Showdown (counter would just waste a turn). If we went down this line then I would be in favour of counter being banned.