Regardless of the banworthiness of Gholdengo right now, which I do not support since I consider it extremely good obviously but not broken at all, I'm 100% sure that once Home gets released Gholdengo will definitely become way easier to check and work around. Mons like Lando-T, Tornadus-T, Gren and Heatran have always seen widespread usage in OU, and are all incredibly good answers to Gholdengo:
Lando-T obviously outspeeds it and threatens it with an EQ or a Stone Edge if it Teras into a Flying type, and it's also bulky enough to tank a Make it Rain or a couple of Shadow Balls;
Tornadus-T will be crazy good with an AV and thanks to Regen it will be able to always switch in and check Gholdengo (unless it happens to be Specs Thunderbolt), and can threaten it back with an Heat Wave or a Knock Off (if it gets it back);
Greninja resists both of its STABS and could OHKO it with a Life Orb powered Dark Pulse or a Specs set;
Heatran is bulky enough to take multiple Shadow Balls without a problem, it resists Make It Rain and can completely destroy Gholdengo with any Fire move.
Other mons that could be very good against it are Moltres-G, Ursaluna, Typhlosion-H, Samurott-H and Arcanine-H, all of which outspeed it with the exception of Ursaluna and can easily 2HKO it, if not OHKO it.
If you think that Tornadus-T with Defog will actually be able to Defog through Gholdengo, then boy do I have bad news for you:
https://www.smogon.com/forums/threads/defensive-nasty-plot-gholdengo-qc-0-2.3714610/#post-9476900

name: Defensive Nasty Plot
move 1: Shadow Ball
move 2: Make It Rain
move 3: Nasty Plot
move 4: Recover
ability: Good as Gold
nature: Calm
tera type: Water/Fairy
evs: 252 HP / 116 Def / 12 SpA / 128 SpD
Oh heck, the set in the thread doesn't even come with an item. Assume Air Balloon or Covert Cloak or something.
Notable quotes from this set's (admittedly NatDex but the Torn-T parts are hella relevant) current analysis:
...notably Tornadus-Therian, the tier's top defogger,...
In regards to the specific EVs on the set, the SpD allows you to survive 2 max invested SpA Heat Waves from Tornadus-Therian from max HP, while the SpA allows you to OHKO bulky Tornadus-Therian with Make It Rain after a Nasty Plot, with the remaining in defense to be able to take hits from the likes of Kingambit and Mega Tyranitar much better after Tera.
Calcs check out and even bring brutal news for Enamorus to boot while still tanking Iron Valiant at least somewhat competently:
0 SpA Tornadus-Therian Heat Wave vs. 252 HP / 128+ SpD Gholdengo: 128-152 (33.8 - 40.2%) -- guaranteed 3HKO after Stealth Rock
0- Atk Tornadus-Therian Knock Off (97.5 BP) vs. 252 HP / 116 Def Gholdengo: 116-138 (30.6 - 36.5%) -- 60.7% chance to 3HKO (99.3% chance to 3HKO after Stealth Rock)
+2 12 SpA Gholdengo Make It Rain vs. 252 HP / 4 SpD Tornadus-Therian: 363-427 (100.2 - 117.9%) -- guaranteed OHKO
252 SpA Choice Specs Enamorus Earth Power vs. 252 HP / 128+ SpD Gholdengo: 260-308 (68.7 - 81.4%) -- guaranteed 2HKO after Stealth Rock
252 SpA Choice Specs Enamorus Mystical Fire vs. 252 HP / 128+ SpD Gholdengo: 216-256 (57.1 - 67.7%) -- guaranteed 2HKO after Stealth Rock
12 SpA Gholdengo Make It Rain vs. 0 HP / 4 SpD Enamorus: 402-474 (139.1 - 164%) -- guaranteed OHKO
-1 12 SpA Gholdengo Make It Rain vs. 0 HP / 4 SpD Enamorus: 266-314 (92 - 108.6%) -- 50% chance to OHKO
252 Atk Choice Band Iron Valiant Knock Off (97.5 BP) vs. 252 HP / 116 Def Gholdengo: 294-346 (77.7 - 91.5%) -- guaranteed 2HKO after Stealth Rock
252 SpA Choice Specs Iron Valiant Shadow Ball vs. 252 HP / 128+ SpD Gholdengo: 214-252 (56.6 - 66.6%) -- guaranteed 2HKO after Stealth Rock
12 SpA Gholdengo Make It Rain vs. 0 HP / 4 SpD Iron Valiant: 500-590 (173 - 204.1%) -- guaranteed OHKO
Nasty Plot Torn-T (yes, it can fit in Defog in NatDex) fares better but not much better:
252 SpA Tornadus-Therian Heat Wave vs. 252 HP / 128+ SpD Gholdengo: 158-188 (41.7 - 49.7%) -- 25.8% chance to 2HKO after Stealth Rock
+2 252 SpA Tornadus-Therian Heat Wave vs. 252 HP / 128+ SpD Gholdengo: 316-374 (83.5 - 98.9%) -- 31.3% chance to OHKO after Stealth Rock
0- Atk Tornadus-Therian Knock Off (97.5 BP) vs. 252 HP / 116 Def Gholdengo: 116-138 (30.6 - 36.5%) -- 99.3% chance to 3HKO after Stealth Rock
+2 12 SpA Gholdengo Make It Rain vs. 4 HP / 0 SpD Tornadus-Therian: 364-429 (121.3 - 143%) -- guaranteed OHKO
AV Torn-T obviously can't use Defog, and the bulky Torn-T calcs above (and heck, even the NP Torn-T calcs, too) indicate it's setup fodder for Defensive Nasty Plot Gholdengo, but at least it tanks hits better:
+2 12 SpA Gholdengo Make It Rain vs. 192 HP / 80 SpD Assault Vest Tornadus-Therian: 222-262 (63.9 - 75.5%) -- guaranteed 2HKO
+2 12 SpA Gholdengo Shadow Ball vs. 192 HP / 80 SpD Assault Vest Tornadus-Therian: 148-175 (42.6 - 50.4%) -- 1.2% chance to 2HKO
It's time to see how much Torn-T really wants to go Tera Fire!
Now if we can transfer Lando-T's with Defog...
there's a Defogger that can crack through Gholdengo.