OK, one of the things is that things that make setting up Gorebyss too hard is that things like Regirock and Probopass are too scared to switch out when they really should, and they stick around to T-wave because the rest of the team is getting swept otherwise. The thing is this: very few teams carry a legitimate special tank / Surf absorber before even carrying a Gorebyss check. (most teams check it through offensive pressure or Scarf Rotom-S) How do you abuse this? You carry U-turning Normal types to lure out Regirock & co., and just play the game of 'Im just gonna stay in and surf' because whatever's switching in takes massive damage anyways. If they are too scared to switch out, well, oh ho ho, a Swellow sweep!
Yeah, this is a metagame where you lose without a Swellow counter, but all of those allow Gorebyss to set up. Something is broken, and I'll give you a hint, it's not Swellow.
Oh, and talking about things too scared and staying in to status Gorebyss, SubSmash Gorebyss works like a charm. Life Orb takes too much HP off, though, so I say maybe White Herb or even Leftovers. It's great for setting up vs. Alomomola, Regirock, etc. and foiling Absol Sucker Punch from revenging you. Yeah, you lose coverage, but it's worth it.