What
trc said is definitely interesting, and although many tiers have thought about banning, nothing seems to happen. However, PU is pretty different to other tiers due to several important factors: firstly terrible hazard removal, this has been addressed on a lot as of the defog/spin users only really pelipper imo would be anywhere close to as good aas it was without defog. Secondly, the setters are also amazing; I see 8 stealth rock setters in A-rank, and without rocks non would drop much in viability (I mean drop directly - not like torterra getting worse due to more fire types), most like the extra moveslot (toxic torterra/extra utility on clef/hp ice or twave probo). Lastly, stealth rock is so amazing due to the nature of tier. Being a lower tier we not only get pokemon that are vulnerable to hazards, making them lowly used, but also the higher tiers take a lot of the good removers - whereas there are enough srocks setters for us to have decent setters. Im still not certain on whether I think a suspect would be best, but regarding what trc said in his last paragraphs, i agree that its not like any pokes/play styles will be broken (we can always ban more i guess), but i dont think we could accurately have 'proper testing'. Its all nice having a minitour or challenging each other to non rocks games, but that isnt enough to accurately represent the metagame which is a big reason why im uncertain.
TBH I feel like a suspect on spikes would be more appropriate. It isnt centralising to the extent stealth rock is, so there isnt a completely different metagame if we ban spikes that we have to judge beforehand whether it would be better or not. There is obviously a few issues with this. firstly if spikes are actually broken, and i think that its the combination of spikes and stealth rocks that makes stealth rocks so threatening and seemingly broken; it along with roselia being the (arguably) best mon in the tier makes me almost always resort to using a hazard remover, and it is much easier to make a non rocks weak than a non spikes weak team (additionally flying types that dgaf about spikes hate stealth rock). Secondly, would this fix our 'problem'? Personally I think it might help more than some people might originally think. This, again, is to do with roselia being amazing and i personally think about roselia/spikes a lot when building (as much as stealth rock). Lastly, why not suspect roselia? This is less relevant now than if we feel spikes/rose is broken, and currently i dont really have a response as it its not like quilladin and galbias fav mon (dwebble) will become amazing. The lack of testing is still annoying for this.
I know this has had a lot less focus than stealth rock, but i completely disagree with a knock off ban/suspect. I personally dont think it is unhealthy for the tier and could be arguable due to the amount of nfe's in the tier (read this para fully before judging). Im not saying that any NFE would be broken in a knock off-less tier, but it certainly makes them much more easier to deal with (especcially in playing against rose - which spikes like i have mentioned, are problematic for the tier). However the main reason i dont think we should not ban it, is because it isnt in fact broken. You may say we dont really have many knock off absorbers, but that honestly reflects more on our dark resists imo. When people feel the need to run poliwrath as a knock off abosrber, they actually run it as a pawniard counter. There are 5 offensive knock off users in a-rank, and poliwrath only switches into one of them which also happens to be the biggest perpetrator. Knock off is not broken on the other 4 (im not arguing that the move has to be broken on every user to ban fyi), it is rather used to let them beat/cripple their checks. Pawniard is a bigger problem due to it having a few counters (wrath/tort/phdef stun and tang come to mind), and although you might argue that knock off is a reason for this, then remember often a move will make a specific pokemon broken (eg swords dance on scyther), or much harder to counter (surf simipour isnt nearly as threatening as hydro pump).
A knock off ban would just nerf pawniard, as that is by far the mon that gains most out of knock and other mons would find other ways to get passed their counters (gunk shot simipour for example)