I found out I can’t exactly vote thanks to not enough GXE, but I’d still vote 
DNB

 Fire’s strong yet manageable. While, yes, 

 Gouging Fire has many strategies, they can all be walled one way or another. I’ll explain my DNB vote, but just note, weather isn’t something considered by me. It isn’t important and many Pokémon thrive off of weather. Tera isn’t important either, as Teraing just breaks everything, and so if sacrificing to beat it, as many other Pokémon might rely on that as well to be beat. Here are some stuff I noticed, however, that 

 Gouging Fire typically uses:
Protosynthesis: Proto is one of the reasons for 

 Fire’s dominance in OU, but it can be countered. 

 Gouging Fire will always get Proto from either Sun, which can be taken away by 

 Pelipper thanks to Drizzle, and 

 Booster Energy, which can be averted via Whirlwind from 

 Ting-Lu. This could also be countered by 

 Skarmory if you give it Sturdy and Roar/Whirlwind. Now, to introduce the Pokémon I believe could be a counter to 

 Fire, 

 Galarian Weezing. While a UU Pokémon, it can also deal with this, as it has moves and two abilities fit for it. This 

 Geezing, the term I’m using to shorten Galarian Weezing, can use Neutralizing Gas to get rid of Protosynthesis, letting it conquer that
EQ and Flare Blitz/Heat Crash/Raging Fury: While each really deserves its own separate argument, I must say that these moves can be countered. Such a counter is 

 Primarina, as seen in the in-depth. 

 Primarina has low defenses yet tanks some EQs. You could also potentially run 

 Specs to maybe be able to defeat it, or Liquid Voice. Mentioned before, 

 Pelipper also handles this threat. It resists those moves, and has a really nice 100 base Defense to boot. Another includes 
 
 Balloon Heatran with Flash Fire. This is completely immune to Gouging Fire, and mostly forces a switch-out. 

 Scor can also potentially deal with this problem, as it’s immune to EQ and the reasons when I talk about Morning Sun. 

 Lando-T also deals with it, as seen below in the in-depth and because it’s I mmune to EQ and has Rocky Helmet to punish those Fire attacks. Finally, let me again introduce 

 Geezing. This time, we can take advantage of Levitate, to be immune to those EQs, and it’s very good base 120 defense to tank those Fire attacks. Or, alternatively, you could run a Water Tera to do that.
Morning Sun: Another reason why 

 Fire is such a problem is because of its recovery. However, there are quite a few options to put a dent in this. First and best, we have 

 Primarina. 

 Primarina can take advantage of Psychic Noise to do so, making 

 Fire unable to recover. We also have Taunt from the many taunters, such as 

 Lando-T, 

 Glowking, and 

 Lu. Another option is setting up Rain, Snow, or Sand with 

 Pelipper, 

 Alolan Ninetales, or 

 TTar, respectively, as that’ll decrease the amount healed by quite a bit. Lastly, we have Toxic stall. Of course, we have our go-to 

 Scor, where Toxic is a staple to it. Toxic will eventually start to deal so much damage that Morning Sun won’t do much, and the 

 Fire is as good as dead. Another Pokémon to be able to do this is 

 Geezing, who also has access to Toxic
Choice Band: Another key thing is 

 Fire’s potential 

 Band, which lets it be a monster with Raging Fury. However, even 

 Bands have their counters. Knock Off. Specifically Pokémon with Knock Off that are faster and can potentially then beat it, or just sacrifice Knock Off, such as 

 Meow as sacrifice, 

 Weavile as killer, 

 Moon as killer, 

 Tusk as killer, and the list goes on
DDance: The last key part to 

 Fire’s reign, it can also be negated. You do this with Haze/Clear Smog, which eliminate the stat changes. This means that 

 Torkoal, despite setting up Sun, is available for this role. Another Pokémon that can use Clear Smog is, you guessed it, 

 Geezing, giving it another way to counter 

 Fire
If you thought I was done there, look at this. These are records of 

 Lando-T, 

 Primarina, and 

 Geezing and how they are able to defeat it.
 0 Atk Landorus-Therian Earthquake vs. 0 HP / 4 Def Gouging Fire: 254-300 (72.3 - 85.4%) -- guaranteed 2HKO
Using the OU Fast Utility set for 

 Lando-T and the OU Offensive Dragon Dance set for 

 Fire, we can see that 

 Lando-T has a clear edge against 

 Fire. It’d 2HKO, and 

 Fire would also do the same with Flare Blitz, assuming that it somehow doesn’t get 

 Lando-T’s Intimidate drop. If it did, it would be a 3HKO instead. Not to mention recoil from the move. “What about if the 

 Gouging Fire Tera’d?” You might ask. Well, if the 

 Fire Tera’d Fairy (the Tera type for this set), EQ from 

 Lando-T will be a 3HKO. And yes, 

 Lando-T is faster than 

 Fire. Now, what if 

 Gouging Fire used Morning Sun while Tera’d? Well, I made a battle to show what would happen: 
https://replay.pokemonshowdown.com/gen9ou-2075126832-4v8knxfjxd89oarhh01uzp57n8lf3wepw
I didn’t even Tera on 

 Lando-T. It just freely bodied 

 Fire. Definitely a counter
 252+ SpA Primarina Moonblast vs. 0 HP / 0 SpD Tera Fairy Gouging Fire: 178-210 (50.7 - 59.8%) -- guaranteed 2HKO
Here we see a 

 Primarina, the OU Assault Vest set, bodying a 

 Gouging Fire, the OU Offensive Dragon Dance set. Now then, is this crazy or what? Especially since, using EQ, 

 Fire can’t even 2HKO 

 Primarina. And using Tera wouldn’t have saved 

 Fire, either, as we can see in the spread. We can, however, take in account that 

 Gouging Fire outspeeds 

 Primarina. However, with EQ 

 Fire still couldn’t beat 

 Primarina, unless it got lucky and crit. Twice. Oh yeah, did I mention that the 3HKO was only a 6.1% chance to? Definitely a 

 Gouging Fire check
This one is too complicated to explain in a damage calculator sense, so here’s the 

 Geezing set I used. The 

 Fire set is the same as always, btw. Note that the set is what I’d use, and not specifically suited to 

 Fire
Weezing-Galar @ Leftovers
Ability: Levitate
Tera Type: Steel
EVs: 252 Def / 4 SpA / 252 SpD
Serious Nature
IVs: 0 Atk
- Toxic
- Clear Smog
- Protect
- Sludge Wave
Now, for the replay. Note that I know what each Pokémon’s moves are, and will be using specific moves accordingly. The replay: 
https://replay.pokemonshowdown.com/gen9ou-2075206575
We can clearly see here, that, while barely winning, 

 Geezing can defeat 

 Fire. Thanks to the talk about my counters to 

 Fire’s strategies above, I won’t need to share the deeper stuff
This is just a piece of how 

 Fire can be countered. This is why I’m voting DNB