Brambleghast is likely gonna be the biggest winner here IF it gets Poltergeist. Wind Rider lets it switch into Zapdos Hurricane pretty comfortably and do this in return:
+1 252 Atk Brambleghast Poltergeist vs. 0 HP / 0 Def Zapdos: 283-334 (88.1 - 104%) -- 31.3% chance to OHKO Copied
It can very easily threaten the evil Ting-Lu + Glowking + Zapdos core that can be annoying the fight against and even has solid MUs vs some of the other mons run on these structures might run like Garganacl and Great Tusk. Granted, it has a bad MU vs Gambit, which may seal its fate. Probably still bad in OU since its Gambit food, but Brambleghast enjoyers will take what they can get.
Lash Out will be completely useless as it was last generation, but MAYBE will have some fringe use on the odd Bisharp or Weavile you see here and there. Its slightly stronger than their current best STAB option, Night Slash, so it will be doing roughly 5 - 6% more on neutral targets after an SD. This may matter in some fringe scenarios.
+2 252+ Atk Tera Dark Bisharp Lash Out vs. 252 HP / 104 Def Zapdos: 356-420 (92.7 - 109.3%) -- 56.3% chance to OHKO Copied
+2 252+ Atk Tera Dark Bisharp Sucker Punch vs. 252 HP / 104 Def Zapdos: 332-392 (86.4 - 102%) -- 18.8% chance to OHKO
Gonna be real, Bisharp and Weavile are really fringe options as in, but maybe the 2 or 3 Bisharp enjoyers can make some heat team where this option can actually work and not be a meme.
Rillaboom was a good Pokemon even without Grassy Glide, but I think it will be a mainstream option once now that it regained this option. Despite the nerf to 60 BP, Grassy Glide is one of the strongest priority options in the game in Grassy Terrain and will give teams some more leeway against some annoying fast threats like Iron Valiant and Walking Wake. Grassy Terrain itself is also bound to become more common, which is a good thing, as it can help certain Pokemon recover off chip damage from hazards and take ground attacks better (looking at you Gholdengo, Kingambit, and Slowking-G).
Also Moyashi mentioned this, but Breloom will be a funny meme in Grassy Terrain now that Glide got "nerfed" to 60 BP.
+2 252+ Atk Life Orb Technician Tera Grass Breloom Grassy Glide vs. 252 HP / 104 Def Zapdos in Grassy Terrain: 369-435 (96 - 113.2%) -- 75% chance to OHKO
Burning Jealousy is useless since no relevant pokemon get the move lmao. Maybe Zoroark-H can pull off some mindgames with it, but I have not seen that mon used since Home dropped.
Toxic is a big wild card since its effect on the meta will depend on its distribution. If it keeps its wide distribution in tact, I think some new users like Corviknight, Gholdengo, Ting-Lu, and Dondozo will make decent use of it to pressure certain Pokemon like Zapdos. Heatran, Hippowdon, and Blissey will all be meta picks again since they aren't as passive. However, if its distribution is largely cut like it was in BDSP, it's effect will depend on the new users of the move, which will be picked out of a hat as far as I'm concerned. We'll just have to wait for the datamine on that. I am hoping the distribution is cut, since switching in Zapdos or Dnite into Toxic was the worst feeling last gen.
enjoyer, this would be very cool to see. Having two high powered stab moves, power whip and poltergeist, on top of having great utility options in rapid spin, strength sap, and spikes, alongside other options like curse or leech seed, could see it being genuinely viable. As you said though, 
being the best mon in the tier is a huge issue for it which limits its viability.
