Heya I've been playing with Fire and Fighting a little too much this gen (due to Dragon struggling with the top types rn, oof :s), and would like to provide a write-up on the viability of some of the Pokemon in both types.
Fire
S
Chi-Yu
A
Ceruledge
Torkoal
Scovillain
Iron Moth
B
Volcarona
Tauros-Paldea
Talonflame
C
Rotom-H
Skeledirge
D
Amarouge
Arcanine

A must have for any fire team due to its near-unresisted STABs and ability to almost cleave through Ghost teams like butter. Choice Specs has no switch-ins (even Blissey can get roasted if Sun is up), while Choice Scarf provides late-game cleaning potential against Ghost teams while also being able to revenge-kill non-Aqua Jet Quaquaval, a threat to Fire teams.

Clutches a lot of matchups due to Weak Armor + Bitter Blade recovering your health being such a nice combo. Colbur Berry, Focus Sash (especially good with Talonflame's Defog), or whatever item you desire for survivability. Its also strong enough to reverse-sweep types like Dragon and Ghost once given the chance to setup a Swords Dance.

provides a Chlorophyll user for Fire teams to take advantage of Sun that Torkoal sets, and also has the coveted Sunny-Beam combo. Its kinda walled by Dragons, but Dragons themselves get 2-3HKO'ed by its Fire Blast so its all fine, I guess? Be wary of throwing around Solarbeams in the rain matchup though...

Sets sun, Body Presses meanies, and sets Hazards and Spin, nothing really changed. Heat Rock is nice for Scov btw, but HDB is preferred if you're not using Defog Talonflame. Also, its nice to know that you can take a hit from +2 Last Mon Standing Kingambit and Lava Plume/Body Press it (its not an OHKO though, but its close enough to be picked off with any priority). This is important since Chi-Yu actually gets OHKO'ed by +2 SO Sucker Punch...so yea...

Another Pokemon can pick off Scarf Quaquaval if using a Choice Scarf itself, and is currently the fastest logical Scarfer for Fire teams. Access to Elec-Grass coverage in Discharge and Energy Ball is nice when fighting Waters, and Dazzling Gleam can revenge-kill Dragons too. Agility + Fiery Dance sets with an Air Balloon is funny, but then you miss out on some important coverage.

Although its overshadowed by its Future counterpart, its still a nice pick due to Bug Buzz + Psychic helping out against Dark/Poison teams, esp once Chi-yu has nuked Clodsire.

Raging Bull breaking Screens in a screens meta. With Bulk Up its quite bulky and can feasibly run Body Press, but lack of instant recovery bar Cud Chew isnt that good. Its a neat scarfer though, but Iron moth and Chi yu are better. Also helps lots with Tyranitar and IRon Thorns, Pokemon which terrify Fire teams otherwise.

The first true Ground-type immunity that carries Defog and Pivoting too. Its amazing speedtier and Priority Brave Birds can come in clutch, letting it pick off Aqua Jet Quaquaval and +1 Roaring Moons if needed. Its also your main response to Annihilape if you want to preserve Chi-yu's health (+Chi-yu can lose the interaction if its not Specs, too)

Is another plausible Scarf user that can deal with Santa, can set screens for Iron Moth and Ceruledge, and has pivoting. Lacking Defog and Pain Split sucks though, and its a slow Choice Scarfer too in today's standards

Oddly, its one of the Pokemon that can stop Roaring Moon on its tracks. Unaware + Torch Song + Hex + Slack Off is great, while Ibone's Curse Spin set is a stallbreaker to be respected.

Iron Defense + CM Sets have to be notable,yes? Too bad it has no priority and is a little worse due to the lots of Special Attackers for Fire

Dog.
Fighting
S
Iron Valiant
Great Tusk
A
Breloom
Iron Hands
Annihilape
Quaquaval
B
Pawmot
Gallade
C
Toxicroak
Lucario
Tauros Formes
Hawlucha
D
Flamigo

Sporting a good speedtier, excellent offensive stats, and a Fairy-typing, its a must pick for any serious Fighting team as its one of the two viable Special Attackers, and it can deal with Corv and Waters well too due to its access to Thunderbolt (but whyyy). Choice Scarf is the usual Go-to, but Expert Belt is quite good (be aware that your next fast mon is like Flamigo, Quaquaval, Gallade, or Breloom however; all of which sit at crowded speedtiers)

Compresses so many roles on one; its a great entry hazard setter and remover, Headlong Rush and Knock Off with a beefy attack stat makes it strong enough to be feared, and good bulk allows for customization to live hits such as Flutter Mane's Moonblast or Meowscarada's Play Rough to OHKO with Headlong Rush or remove its item.

Clutches matchups and can flip the script on Ground and Water teams. Also picks off Roaring Moon in the case that it managed to setup. Scarf Breloom, while niche, is great as it allows you to spook Barraskewda and Iron Valiants, for instance. Life Orb lets you kill Santa, but now they know ur not sashed....

Tanks everything. He's able to sit on threats from both sides of the spectrum from Scarf Iron Valiant, Flutter Mane, and Santa, to surviving Roaring Moon and Meower. Tbh In my opinion he's kinda broken that way, but there's bigger threats to deal with right now.

Monke. He's been explained to death by the other posts, but helps a lot in fighting which would otherwise struggle with bulky walls just sitting on them. Roseli berry is a nice way to spook and exorcise Flutter Mane, but Leftovers and Punching Glove are more reliable. Oh, and he's the one that deals with Skelidirge the best imo.

The other mon that can deal with Skeledirge. Choice Scarf sets are the most common, though Aqua Step + CC + Ice Spinner + SD or U-turn or Aqua Jet are fun, too.

Revival Blessing is bonkers, but making your team very weak to Ground isn't. Still broken anyways though, but sometimes just having a second Iron Hands or Annihilape is the way to win. It also notably 2HKOs Corviknight with Thunder punch and has access to Bolt-Beam with Tpunch-Ice Punch + Mach Punch though. Encore is interesting against setuppers like Dondozo so that you can smack em with Valiant, but you're gonna accept that Pawmot might die trying to lock Pokemon into moves.

Scarf or Band Gallade stronk with sharpness.

When Annihilape goes it's gonna rise in usage, maybe. Priority in Sucker Punch is cool for the Ghost matchup, as well as Gunk Shot/Eq for Fairy, but its a tad slow. It gets Bullet Punch too, but Lucario can do that better. Water immune doesnt come to play as much as Barraskewda can just click Psychic Fangs and it gets owned by Santa's Ice beam.

Has been powercrept nowadays, and the common-ness of priority makes him sad. :(

Nasty Plot set can make it a neat Special Attacker, as it has Dark Pulse too to shoo Ghosts away. Its not enough to deal with Annihilape however. Bullet Punch neat for Flutter Mane, though Iron Hands can just try to 1v1 it instead of investing a slot for it.

Screen Breaking + Speed makes it a nice Scarf user

Scrappy good with Scarf, lets you punch Ghosts.
Thats all for me, thankie for reading if you made it this far
