Endless stall is one of those things that I don't understand why nothing has been done. I've said it about three times now: just ban Heal Pulse and be done with it. Heal Pulse's only theoretical legit use is to bounce it off an opposing Magic Bouncer to heal yourself, but that's completely pointless when Recover and its clones exist. That move is the crux to the majority of the infinite stall strategies. So, banning it kills a lot of those while having zero impact on any legit strategy.
Banning duplicate moves on the same moveset (say Tackle/Tackle/Tackle/Recover), kills a bunch of whatever's left over and also has zero impact on legit strategies.
As for Imposter, as someone who only uses it as filler in experimental teams and on a dedicated PP stall team, where it's just filler on a less-than-experimental team, I can safely say you can scout and check things without it, set-up sweepers included. Heck, some of my newer teams don't even run Unaware. The keyword to remember in set-up sweepers is set-up. If you don't let them set-up, they'll have trouble accomplishing much.
I'm not a fan of Imposter and wouldn't be sad to see it go since I feel it's stifling the tier. I mean, why try to come up with better ways to scout or control momentum when you can just throw an Eviolite Chansey at the problem? On the other hand, Imposter is not a priority of mine. I'd rather much look at Sturdinja, who auto-wins any match-up that is not against a check or counter, requires multiple checks and/or counters to reliably handle if the Sturdinja user is competent, and pretty much auto-wins the game for the user if those checks and counters are gone, whereas even nasty stuff like Refrige Kyu-B can be beaten without dedicated checks and counters via smart play.
Then there's mega-stones that let Pokemon use banned abilities. The abilities are banned for a reason and the loophole is silly and doesn't even make sense. Why is Medicham-Mega allowed to use Huge Power but not Azumarill? Why is Gengar-Mega allowed to use Shadow Tag but not Wobbufett? Especially when, in both cases, the former is much more dangerous than the latter. I think the offending mega-stones need to be banned, though the mega-mons themselves can stay.
But let's worry about stones and undead bugs later. The conversation is running in too many directions as is. Illusion, Imposter, and infini-stall is broad enough.
Banning duplicate moves on the same moveset (say Tackle/Tackle/Tackle/Recover), kills a bunch of whatever's left over and also has zero impact on legit strategies.
As for Imposter, as someone who only uses it as filler in experimental teams and on a dedicated PP stall team, where it's just filler on a less-than-experimental team, I can safely say you can scout and check things without it, set-up sweepers included. Heck, some of my newer teams don't even run Unaware. The keyword to remember in set-up sweepers is set-up. If you don't let them set-up, they'll have trouble accomplishing much.
I'm not a fan of Imposter and wouldn't be sad to see it go since I feel it's stifling the tier. I mean, why try to come up with better ways to scout or control momentum when you can just throw an Eviolite Chansey at the problem? On the other hand, Imposter is not a priority of mine. I'd rather much look at Sturdinja, who auto-wins any match-up that is not against a check or counter, requires multiple checks and/or counters to reliably handle if the Sturdinja user is competent, and pretty much auto-wins the game for the user if those checks and counters are gone, whereas even nasty stuff like Refrige Kyu-B can be beaten without dedicated checks and counters via smart play.
Then there's mega-stones that let Pokemon use banned abilities. The abilities are banned for a reason and the loophole is silly and doesn't even make sense. Why is Medicham-Mega allowed to use Huge Power but not Azumarill? Why is Gengar-Mega allowed to use Shadow Tag but not Wobbufett? Especially when, in both cases, the former is much more dangerous than the latter. I think the offending mega-stones need to be banned, though the mega-mons themselves can stay.
But let's worry about stones and undead bugs later. The conversation is running in too many directions as is. Illusion, Imposter, and infini-stall is broad enough.