Dynamax is definitely meta defining but... it’s supposed to be? There are so many ways to stall out those 3 turns and if your opponent doesn’t make good use of that window it puts them at a huge disadvantage.
I’ve seen people mention multi turn moves. Every mon can use sub and protect. People will adapt eventually. Now setup mons are a whole different story but the point is, nobody is really making an effort to counter Dynamax outside slapping a Ditto on.
Are the current OPs really going to be any less dominant with Dynamax banned?
As people have mentioned a million times in this thread, there is counterplay for basically everything in the game but its important to note how
niche and specific that counterplay is, and whether forcing its use is detrimental to your ability to cover other threats. For example, you could argue Zacian isn't broken if you just run multiple Choice Scarfed Ground / Fire-types - this is clearly ridiculous logic, because at a certain point trying to prepare for Zacian is therefore highly limiting your valuable teamslots / moveslots and you're probably super super weak to one of the other 50 threats in the game as a result. There is no Pokemon in the game thats unbeatable, but there are some that require such dedicated and niche counterplay that it turns teambuilding into just "pick your poison" - this is ultimately why we ban stuff.
By comparison, something like Lando-T which low ladder people were clamoring for a ban for the past 2 gens barely forces your hand at all in teambuilding - you basically need a couple of ground immunes / resists and a couple of Pokemon that can hit it super effectively, but even if Lando-T didn't exist you'd literally have these anyway because these are useful slots to have against tons of other Pokemon in the game.
With regards to all the options that people list off to deal with Dynamax: 1) They are highly tailored to beat Dynamax and therefore niche and 2) they are not even reliable at doing it anyway. Let's go through them.
1) Protect / Detect / King's Shield / Baneful Bunker - These are probably the most viable out of all the options because they are useful without Dynamaxing, but let's at least consider how they work.
Best case scenario for a Protect user vs Dynamax is this: Opponent Dynamaxes in front of your Protect user, and you Protect first turn, take 25% damage and they get the boost they want. Turn 2, you have to either sit in (presumably if you can KO the opponent then they wouldn't Dynamax in your face though) and survive an attack, or switch into a resisted. Turn 3, you can Protect again to lose 25%, let them boost again. Now you've staved off the initial onslaught, but you've still taken significant damage, facing down a healthy threat with 3 boosts, and this is even in the
best case scenario. This, and the fact that its forced you to use Protect on a Pokemon that you may not have wanted to, just to apparently "win" this situation vs Dynamax.
2) Substitute - Same as above but potentially even worse, as you have to be faster than the Dynamax Pokemon for it to be reliable (what if they just Max Airstream on your Sub and outspeed next turn lol), and again, you're surrendering a lot of health over 3 turns just to apparently "win" the exchange. Not to mention, if you're proactive with Substitute and get it up early, your opponent just isn't going to Dynamax in front of you until its gone anyway. Only mon that can consistently do this is Grimmsnarl, but it still gives away 3 boosts to the opponent and you lose 75% for that "winning" exchange.
3) Multi-turn moves - We shouldn't even have to mention this because they are so blatantly terrible. Yes, they can temporarily do a job against Dynamax Pokemon, but you are definitely still taking a lot of damage on the turn you surface. Outside of Dynamax, these moves are a liability, for two reasons. Firstly, they are complete set-up fodder for something like DD Gyarados, DD Dragapult, SD Hawlucha etc either before or after Dynamaxing. Dive gives a completely free switch-in to Dracovish if it wants. Dig gives a free switch-in to Gyarados and Hawlucha. Secondly, in your own post you are advising people to use more Protecting moves, which makes multi-turn moves completely and utterly useless! I cannot think of a single instance where I'd want to use this with the exception of Phantom Force Dragapult (which still gets hit by Ghost type moves lmao)- every single other one is absolute trash and will be fully taken advantage of by anyone good.
4) Priority - as previously stated, the vast majority of good priority users got axed, and the ones that currently exist can't do anything against the good Dynamax Pokemon.
5) Focus Sash - gets brought up a lot, you have to keep hazards off the field, no weather, and there's also no Focus Sash user that reliably beats all Dynamax mons so where do you even choose where to put it?
Honestly, nobody is arguing that Dynamax is uncounterable but I think the vast majority of good players will acknowledge that the counterplay is super niche, and means that e.g. even if you get around Gyarados using Dive Toxapex or some rubbish like that, guess what you now just lose to set-up sweeper XYZ because you don't have scald. Its beatable but its impossible to make a team that consistently matches up well against Dynamax users that isn't horrifically deficient in other areas, which, in the long-term, just turns the game into one of team match-up.