The 20th anniversary generation and also, somehow, the Goldilocks generation?
To this day, the 20th anniversary generation is the only one to be on two systems with no backwards compatibility option, and it was also the first generation to introduce Pokémon while retaining compatibility - it was also the last one to have games on a dedicated handheld for now. A lot of the old series annoyances, such as the need to have specific “HM friends” for world exploration, were also done away with and not a moment too soon. It even served as a temporary farewell to Mega Evolution in a limited fashion by keeping it until the end of the game, and a full farewell to the concept of a “National Pokédex” in game - you could bring anything into a Sun or Moon game, but only certain things counted with the full collection offloaded to the 3DS’s Pokémon Bank application. And for better or worse, it also gave us Incineroar.
Each pair of games in the generation offers a very different experience, all seemingly aimed at different audiences. The original Sun and Moon are the best for story players - yes, the cutscenes are belligerent, numerous, and unskippable, and you don’t normally go to a Pokémon game for its story. But the main story of Sun and Moon is a bit more logical than what the Ultra games provided as an “alternate take”, and it’s probably the most balanced difficulty wise of the three groups.
Although Ultra Sun and Moon don’t quite have the same story chops, it does speak to me as a pretty hardcore Pokémon player in its challenge. I don’t know if they realized what the fate of post-Switch launch 3DS software would be compared to what had come before it on the 3DS, but they created a game unparalleled in its difficulty for a main series Pokémon game outside of perhaps the second part of Scarlet and Violet’s DLC (complimentary). There’s a boss whose battle theme would not be out of place for a baseball closer in terms of the sheer amount of “this is gonna suck” that follows in Ultra Necrozma. And if you felt the team options in the original Sun and Moon were lacking, the Pokédex was expanded by a third (300 to 400) for additional team options.
I’ll admit that to this day, I’ve never actually rolled credits myself on the Let’s Go games - forced motion controls and the oh so overused Kanto? No, thank you - but I do appreciate what they represent. Following on from the success of Pokémon’s most lucrative spinoff in Pokémon Go and a counterfactual to Ultra Sun and Moon, the Let’s Go games serve as a fine entry point for younger or more casual Pokémon players. And the Let’s Go games provide a whole other take on the series’s experience concept by rewarding catching Pokémon instead of focusing on battles. And hey, anime-accurate Pikachu if that’s your bag and you pick their version.
If you’re looking for wildly different experiences in your Pokémon games, it’ll take two different systems but you can have an experience that’s as easy or difficult as you want it to be. I still can’t forgive them for the rudo cat, though. Primarina 4 life.