I think we need to have some way to reduce harm caused by the fully passive stallmons, mainly Skarmory, but possibly also Chansey. This, however, doesn't mean we have to threaten them offensively, there are other means of reducing their impact on our PS pivoting, and picking and showing them would be poll-jumping, but I think everyone sees at least the several obvious ones.
I think it would be bending-over-backwards to try to win against the likes of Megagross and its powerful Bullet Punch. That thing just looks as too perfect counter to try to turn it over.
I also have no problem with losing to physical Jirachi, Naviathan, Magnezone and other bulky steels that fight "fair" or "somewhat fair". We can pivot out with a harm to their, often not stellar anyway, offences.
Losing the manfight against Cawmodore is a non-issue either. If CAP22 gets to manfighting Cawm, the battle is lost anyway. And, as was multiply stated, we can pivot out from him, where Parting Shot covers some double-switch tricks and any sane CAP team needs to stop Cawm in its tracks anyway. At least once (because if Cawm gets to setup twice, something's not right either).
The problem is slower bulky steels with pivoting moves, that force a guessing game with us on the shorter end - Magnezone and Jirachi can do so, but don't do that as often as others. Besides, Magnezone's Volt Switch can be quite easily (Colossoil likes this) blocked in an advantageous position (trapper, free hazards, whatever) by a Parting Shot and Jirachi runs U-Turn less commonly, because it needs those moveslots. (Mega) Scizor, however, is a completely different story. This thing is there often, runs U-Turn regularly, as well as strong Bullet Punch. That said, we probably don't need to beat him in a manfight. Again, that seems like going directly against the nature of Fairy/Fighting Parting Shooter. I'm, however, of a belief that we want to be threatening to him - one way or another - enough to discourage the switchin. Or at least, discourage the switchin enough that CAP22 isn't "Scizor coming in freely, forcing CAP22 out normally" all the time.
So, summary: I have no problem with losing to multiple of the threats, but we need to threaten the passive stallmons enough to reduce harm coming from them and we want a way to threaten Scizor on predicted switchin.