Instead of banning Mew, would it be reasonable to ban Imprison? I know that normally it is preferable to ban the Pokemon instead a specific move it abuses, but you could argue that Imprison is the problem in this circumstance.
Also, another filler option with Mew is Encore. Encore can punish Substitute users, make Trick users take their Choice Item back with prediction, and block opponent's Encore after using Imprison.
Move bans should only be considered when the move itself is creating either a broken, uncompetitive, or unhealthy result on nearly everything that learns it.
In this instance, it isn't simply Imprison itself that is breaking Mew, but rather the combination of Imprison + Transform in order to force the opponent into Struggling themselves to death.
Bear in mind, I'm not arguing for an Imprison + Transform ban, either, as this is a combination that has already existed in the past 5 generations (Smeargle) and has generally been shown not to be overbearing, with the exception of Smeargle's abuse of older gen Sleep mechanics.
Instead, Mew is the sole focus for a potential ban/suspect in this instance, on account of its usage of these moves AND its very competent 600 BST that enables it to outspeed foes and/or withstand attacks, both of which enable the strategy to be viable in the first place. Additionally, Mew is so versatile that it isn't
just limited to the Imprison + Transform strategy, either. It has perfectly solid offensive stats and a plethora of attacks and setup that allow it to make use of several offensive strategies. I personally find Choice Band to be the best at covering mostly everything that threatens the Imprison + Transform set's weaknesses.
Umm, while we're all debating about Mew, i think Sableye is inherently more broken.
In this meta, with the removal of z-moves, trick has become incredibly more useful, sableye can abuse this along with trick to essentially beat any mon it can live a hit from (barring dark types).
While it can struggle with mons with choice items as well, it can still beat mons that have low pp on the move they use (ex: Banded Pyro Ball Cinderace).
But, Sableye beats 100% of the time any mon with a choice item by running substitute with disable.
So two of its sets can destroy a large majority of the metagame:
Scarf trick, as well as Sub+Encore+Disable with roseli berri.
Out of AllFourtyOne's "VR", it beats all of the entrys with one of its two sets except dark types and dual stab running Sylveon (Honestly will become a thing)
This puts an incredible strain on teambuilding, forcing the usage of a dark type or some other mon that can deal with it.
I'd like to hear different opinions on this matter.
I absolutely agree that Sableye is a huge threat, though for the time being, I believe we need to see further usage of it before coming to a conclusion, as it (among many other things) is still a very recent development.
That said, I do believe that Trick/Switcheroo + Choice items (for brevity's sake I'll just say Trick from now on) in general are mostly the inherent problem at hand, rather than just Sableye. I bring this up because, with Dynamax banned, we are now in the only generation of 1v1 to not have any means of blocking Trick beyond using Sticky Hold or bait items like Black Sludge.
Unlike the case of Imprison I mentioned above, Trick is absolutely abusable on nearly everything that gets it, even if on some pokemon like Cofagrigus, you'd only be using it for the sake of effectively deleting stall, much to the same effect of Perish Song when it was allowed.
The difference here, however, is that stall is not forced to get a OHKO against Trick users in the same way they were required to quickly KO Perish Song users, since the battle is actually allowed to continue until a pokemon drops to 0% HP, giving the stallers plenty more opportunities to KO the opponent before it's too late, assuming they even have a move to KO with.
In my opinion, it is absolutely Trick at fault here, rather than particular users, as the combination of Trick/Switcheroo + Choice items
alone is enough to completely dismantle many stall strategies available to us right now. Added bulk to withstand attacks or the power to KO foes after Tricking them is just the icing on the cake.
With regards to Sableye, as far as things stand in the present, I do believe it is worth looking into as a potential suspect, but only if we look into Trick as a whole first, since it would be a massive waste of time to have to resuspect Sableye if Trick were banned after the fact, though it would really depend on whether Encore + Disable on its own is still enough to ban Sableye.