You gonna tell me what Kalos gym teams all were? I can remember some of them, but even they are pretty meh. Unova teams are decent, but most of them are only 2 or 3 Pokemon also. You have Sinnoh which in my opinion has some of the weakest gym and Elite 4 teams, Hoenn is decent but still true, etc.
Vivillion/Surskit.
Aurorus/Tyrantrum. (technically I think it was the pre-evos, but it was the two fossils from this region which is cool and memorable).
Hawlucha, Machoke, some other non-Lucario, non-dark mon with no coverage.
Weepinbell, Skiploon, Gogoat.
Emolga, Magneton, Heliolisk. (And they COULD have done a lot more with this one than they did and I hate it. Just give us a good volt turn team for once!)
Mawile, Sylveon, something else.
Psychic. I remember nothing about this gym other than the aesthetic. A lot of Psychic mons all fit the same mold, fast special attackers, which is good for effectiveness, bad for me remembering if it was Kadabra or Espeon that I one-shot.
Avalugg, Cryogonal, Abomasnow, I don't recall anything else because it's ice, you just spam SE moves and move on. He abused hail which was cool, but also did not matter in any way.
Checking my list...Yep, I was right. Except that I assumed Wulfric had more than 3 mons(WHY does GF want Ice to suck so hard?) and of course I ignored Olympia's team entirely. Every one has a Gen VI mon as their ace, which helps(I only remembered Surskit on Viola but just assumed she'd also have the regional butterfly with a cool gimmick), and this gen was small teams, which made it easier.
It's interesting you specifically chose Kalos for this list. Because the gym teams in Kalos suck. Grant's gimmick is cool and I wish we saw it more often(GSC Brock is the only other time a Rock-specialist uses the fossils IIRC), Valerie is reasonably well-made, and Clemont is at least positioned well to tell the player "Catch a damn ground-type for this fight", but none of them are as challenging as various random route trainers. But even with that, I remembered their teams.
My unpopular opinion: The decision to base the Regions on stuff IRL is really interesting, but I think limits their design options far too much. GF would be much better off if they decided to just scrap real-world inspiration beyond "ooh, let's pull in some Amazon Rainforest over here, and toss in a battle atop the temple at Tenochitlan for the final fight. Oh, and I want a really tough poison gym, pull up the list of venomous Australian creatures for the Zubats of this game."