We need less monotype gyms after mid game
I can understand keeping Rock-Paper-Scissor dynamics early game, but if the Rival can bother not being mono, official gyms should be too. Again, mid to late game
I say this a lot but this is something the older games tended to be more interesting about (deliberately or otherwise). Think of how most of Koga's gym trainers use Psychic-types while he himself specialises in Poison-types for instance. Or Viridian Gym where even though the trainers are explicitly said to prefer Ground-types they also use Fighting and Normal and Poison. Ironically one of the silver linings of DP's pathetic regional dex was that, since there just weren't enough Pokemon of each type to go around, rather than just doing what you might call "the Ecruteak model" where the entire gym just uses the same evolutionary family, you get weird little outliers in the latter three:
-Canalave Gym (a Steel-type gym) has trainers with Skorupi and Azumarill
-Snowpoint Gym (an Ice-type gym) has trainers with Tentacruel, Pelipper, Golduck, Steelix, Floatzel, and Quagsire, while Candice herself famously uses a Medicham
-Sunyshore Gym (an Electric-type gym) has trainers with Mr Mime, Kadabra, Bibarel... and Medicham and Steelix again! Truly the Swiss Army knives of Pokemon. Oh, and Volkner infamously uses Octillery and Ambipom
You don't even really need a non-monotype gym if you just let the trainers be a bit jazzy in their team picks; it's at least more exciting than fighting a bunch of wimpy trainers all using the same unevolved Pokemon over and over. But if there's a decent diversity of Pokemon of a certain type available to use, I don't see the harm in a monotype gym per se
if the foes you face have enough variance between them to keep things interesting. Let's say you have a Flying-type gym and the gym trainers have Electric/Flying Pokemon, Grass/Flying Pokemon, Ground/Flying Pokemon, Rock/Flying Pokemon, Bug/Flying Pokemon, Steel/Flying Pokemon, and so on. That's diversity enough that you can't just roll through and mindlessly click A to smash everyone with the same move: some won't be weak to Rock, some won't be weak to Electric, etc. Ironically Fortree Gym is a perfect example of this I hadn't even looked up before writing that - compare RS's bland all-but-one-are-Normal/Flying group to Emerald's much improved roster:
Though the issue that remains with Emerald is that the trainers share a lot of their picks with Winona. In a perfect world every gym would be like Emerald's Mossdeep Gym, in which there's enough Psychic-types in Hoenn that the 12 trainers in the gym use 9 different species among them, with only one of those in common with the gym leaders (and even THAT's leaving a few out - none of them use Baltoy, Beldum, Metang, Staryu, Starmie, or Chimecho).
It's obviously an atypical example but I also really liked how in HGSS the gym trainers (mostly) all had powerful evolved Pokemon; a few of them also had Hoenn and Sinnoh species to keep things interesting. They're all on the level of what a proper eighth gym should feel like, but most of the designated eighth gyms we've had... are pretty lame tbh now I think of it.
Like:
Viridian - the diversity of types was, as I said, quite cool and the Pokemon are mostly powerful. Could have been a bit better though, there's a few too many unevolved Pokemon for my liking. FRLG actually improved on RBY a lot in that regard
Blackthorn - quite pathetic, though there's a very noticeable progression as you only fight a fully unevolved team once. Dragon Rage is admittedly pretty powerful at this stage in the game as it 2HKOs or 3HKOs pretty much everything
Sootopolis - without a doubt the most pathetic final gym we've ever seen or hopefully ever will in its original iteration. Luvdisc at least has the excuse of being a single-stage mon but why am I fighting trainers with Goldeen? Wailmer? Feebas? Carvanha? Fucking
Azurill? ORAS thankfully did largely correct this.
Sunyshore - pretty mid in DP/BDSP, improved noticeably in Platinum
Opelucid - very similar to Blackthorn in most regards: Fraxure and Zweilous' high evolution levels (and the fact that the gym leader uses Haxorus) means that everyone's using the same pool of 4 species. I find BW's iteration of this gym incredibly unmemorable
Humilau Gym - this is pretty good, particularly in Challenge Mode. Everything you fight in here is fully-evolved and B2W2's massive dex is used to its fullest extent
Snowbelle Gym - actually pretty decent and all unique species, though this gym never really sticks out in my memory for some reason
Hammerlocke Stadium - I've never played SwSh all the way through but I really like the slightly wacky vibe of this gym. This is actually pretty much as close to a non-monotype gym as we've had tbh.
