Gym Leader Interactions: Note of course this is an anime thing, in the games the Gym Leaders seem to know each other well enough. Now in the games this is likely because there are only 8 Gyms per Gym Challenge League; meanwhile the anime takes a more realistic approach that a region is pretty much as big as a country so there are dozens of Gyms in each region. I feel that is an important detail to remember because now it's kind of understandable why the Gym Leaders wouldn't really know each other cause instead of there just being 7 others its over 70 others (okay, maybe that's a bit of a exaggeration, though I'd say maybe at least a Gym Leader or two (possibly even three in certain cases) for each Type is probably more of a reasonable assumption). So, meeting the other Gym Leaders have been explained away, so how about just knowing about the other Gym Leaders even the ones nearby. Now that's something the anime is guilty of, understandable for a world with dozens of Gym Leaders you wouldn't know the ones from faraway towns/cities, but neighboring towns/cities they really don't have an excuse why they don't.
This post from another thread got me wondering about Gyms. It's still (deliberately, I'm sure) so vague how they run after eight generations.
Now, obviously, there are official gyms and unofficial ones (that is, Pokemon League-endorsed and not) and official ones have to be up to a certain standard. In the anime Forrest has to prove that the Pewter Gym is up to scratch - one of the adaptations mentions that if a Gym Leader loses three times in a row, they are stripped of their title, and the manga has a qualifying test where none of the candidate's team can faint.
The games have eight gyms in each region and seemingly only those eight. Gameplay and story segregation obviously plays a role in this, but there are occasional indications to there being more gyms than the ones the player sees. Brendan and May in RSE imply that Slateport getting a gym is an inevitability, but it's ambiguous whether they mean that one will be opened for no particular reason or that it won't get one until another gym in a different area shuts down and they need an eighth one somewhere else. Galar does seem all-but-confirmed to have one gym for each type - the gyms not visited by the player are just minor league ones. So presumably, the minor league gyms do not count towards entering the Pokemon League - it's unclear if they can give out badges unless they're major, but it would appear not.
The anime, as mentioned, does have multiple gyms: these appear to be both official ones - since we see trainers in all of the first six regions with unidentified badges - and unofficial ones, like AJ's Gym and the Kas and Yas Gyms in Dark City, both of which are trying to get certified.
It's interesting that the unofficial gyms we see never share a type with established ones. So does that imply that there is - or can only be - one Gym of each type in a region? It certainly seems this way in the games. In Unova we see that Cheren literally takes over the Normal-type mantle from Leonora - he even gives out the same badge. If she was still operating, would he have had to choose a different type? If nothing else it seems kind of pointless for people to set up multiple gyms of the same type when you could just go and train at one that's already there. A swimmer in Unova mentions that he will seek out Water Gyms in different regions - why would he need to do this if Unova had more than one of its own? In B2W2, Marlon is inferred to have only recently opened his Gym - could he not have opened it if Cilan, Chili, and Cress were still running theirs?
What also seems concrete is that it's only one gym per area. Cilan, Chili, and Cress do not operate separate gyms, even though they logically should - instead, they run one together. Sabrina famously challenges the Karate King for the right to be Saffron's official gym - the idea that the city could simply have had two gyms was clearly not on the cards. Because of this, it does not give out a badge. So does Kanto no longer have a Fighting-type gym? Would they have to set up elsewhere to be one?
So yeah I'm curious as to whether there's only one gym of each type allowed in each region or whether any old Tom, Dick, or Harry can start setting them up as and when they like. Given the weird cult of personality the Blackthorn Gym has around Dragon usage it's hard to imagine them tolerating another Dragon gym in Johto (or in Kanto come to that). Or Sabrina allowing any pretender Psychic gyms in Kanto to exist.