Salamence by legend of DP OU is uncounterable because of dracometeor + fire blast + outrage.
The thing is, pretty much no one runs draco meteor on Salamence anymore since walls aren't nearly as prevant as they where in DP. I am safely say that I have switched in Hippowdon and Slowbro into Salamence without care, only once in a long while will someone actually have a mixmence. I haven't seen mix mence at all in large numbers at all since this time last year.
Even then, that kind of Salamence can't sweep, so yes it broke on of your walls, possibly opening up a sweep, but that is about the limit of mixmence. If you can stop the other sweeper well enough, that Salamence is left pretty much useless.
This is me speaking from complete ladder experience, so if you try to go against it with theorymon, you are not going to get far.
I am not Scarf Wynaut on Pokemon Showdown. I am PrincesoBubblegum