With a lot of Physical Attackers and no Defiant / Competitive Pokemon this team is very Intimidate weak. To fix this, I think you could replace Hawlucha with Galarian Zapdos. Zapdos also gets Coaching which is useful, and also access to a higher Attack Stat, stronger STAB Brave Bird, and possibly Taunt to shut down Status or Trick Room. I'll go over that later, but first:
Garchomp
Garchomp is my favorite Pokemon of all time, so it was going to make it into this team no-matter what. Thankfully, I think it synergizes quite well with them. It's here to deal raw damage and be a potential receiver of Hawlucha's Coaching.
Well... technically it doesn't synergize well at all with Rillaboom's Grassy Terrain halving the power of its Earthquake. Instead, probably run Stomping Tantrum instead. As well, Outrage is pretty bad in Doubles, especially outside of Dynamax, as you don't get to choose your target. Instead of Choice Band you could also run Life Orb with Protect + Stomping Tantrum + Dragon Claw / Outrage / Swords Dance + Rock Slide to maintain the Damage output while also not locking yourself into a move. Also I'm not going to replace this with Landorus-T because
1. You wanted to keep it lol
and
2. Landorus-T literally only learns Earthquake as physical Ground STAB ♂️
Rillaboom
So I'm looking at the set and the moves seem to me like they would work better for a supportive Rillaboom, however the EVs and your description say otherwise. For an offensive Rillaboom, why not try:
Rillaboom-Gmax @ Miracle Seed
Ability: Grassy Surge
EVs: 4 HP / 252 Atk / 252 Spe
Adamant / Jolly Nature
- Swords Dance
- Grassy Glide
- Wood Hammer / Knock Off
- Fake Out / Protect
Swords Dance can be extremely threatening to boost Rillaboom's Attack to sky-high levels and turn it into an great sweeper. Wood Hammer can be used if you want a strong non-Max move that can hit harder than Grassy Glide whereas Knock Off can remove Eviolites, Berries and more that would otherwise be scary to deal with. The last move is mainly chosen if you want more supportive capabilities or if you just want to Protect Rillaboom for a turn.
Hawlucha --> Galarian Zapdos
Like I said before, this thing completely counters Intimidate and is much better than Hawlucha.
Zapdos-Galar @ Adrenaline Orb / Life Orb / Assault Vest
Ability: Defiant
EVs: 4 HP / 252 Atk / 252 Spe
Jolly / Adamant Nature
- Brave Bird
- Close Combat
- Taunt / Stomping Tantrum / Throat Chop / Blaze Kick
- Coaching / Detect / Throat Chop / Blaze Kick
A lot of choices of moves to choose from, but I think Taunt is good if forgoing Taunt on Whimsicott to shut down Trick Room. Rest are coverage for things like Celesteela, Spectrier, Dragapult, Regieleki, Torkoal, Metagross, etc. If you're running Life Orb on Garchomp maybe run Assault Vest + 4 Attacks or Adrenaline Orb? I don't know lol.
Whimsicott
Focus Sash + Defensive investment is usually not good. Instead, try Max SpA + Max Spe with Moonblast + Tailwind + Helping Hand + support move of your choice (e.g. Taunt, Charm, Encore, Protect (to avoid Fake Out), U-turn, etc.)
Primarina
I'm not sure why you would use this over Tapu Fini; it provides Misty Terrain support for Garchomp as well as being able to turn into a devastating sweeper with Calm Mind.
Tapu Fini @ Leftovers
Ability: Misty Surge
EVs: 244 HP / 12 Def / 196 SpA / 4 SpD / 52 Spe
Modest Nature
- Muddy Water
- Moonblast
- Calm Mind
- Protect
Pretty straight forward; EVs from Smogon:
Its HP maximizes recovery off of a single turn of Leftovers healing. ... Tapu Fini's Speed allows it to outspeed common base 100 Speed Pokemon such as Charizard and Zapdos when at +1, often from a partner's Max Airstream or Regieleki's Electroweb.
Marowak-Alola
I don't see that much of a problem with Rotom, as most of them are Rotom-H to combat sun. It is pretty much ruined by Garchomp. Alolan Marowak's only niche is its signature item Thick Club, which doubles its Attack. You did not give it that, so why don't we try something else?
This team lacks much Intimidate support, and if you want to keep the Fire-Water-Grass core, Incineroar is a great option to have.
Incineroar @ Sitrus Berry / Safety Goggles
Ability: Intimidate
EVs: 244 HP / 76 Def / 188 SpD
Careful Nature
- Fake Out
- Flare Blitz
- Parting Shot
- Taunt / Darkest Lariat / Snarl
Again, EVs from Smogon allowing it to survive +2 GMoltres (Goltres?) Max Airstream and -1 Urshifu Close Combat.
If no Taunt on other Pokemon, probably use it on Incineroar to shut down Trick Room. Otherwise, Dark STAB is also nice. Safety Goggles if you want to better combat sun, or Sitrus Berry to avoid 2HKOs.
Those are all the comments I have for your team. I hope I helped! :)
