Is currently the era of Pokémon in the awkward place of being too old by Current but to recent to be Retro.
For my personally the Diamond and Pearl generation is the last one I feel any Nostalgia for, and them being still the last Gen to get remade I could cite to back me up on that, but I tell the Fandom in general sees Black and White as classic already, it's games were after all on the same Console as the the Diamond and Pearl games.
Sun and Moon for the Anime definitely began the era of the original format being largely abandoned and the movies being their separate continuity. I personally essentially stopped caring about the Mainline Anime because I couldn't stand the new Art style.
This is reflected in XYZ now being the most recent era not easily accessible on legal streaming sites since it's been taken off Hulu and about to leave Prime in 10 days. Their Games are not the most recent Games not playable on the Switch however.
I have a persona Fondness for this Generation. I basically skipped Black and White when it was current so it was my first time watching current Pokémon with something resembling my current mindset towards media in general. Also my first time watching a spot Brock series and I still think it's supporting cast dynamic works better then what little I've seen of the Best Wishes Anime. And I think the Mega Evolution Specials are some of the most underrated Pokémon Anime content, I still get a kick out of how Lysander reminds me of Alexander Luther Jr of 90s DC Comics.
I did and still do have mixed feelings about Mega Evolution as a concept. I think I'm glad it didn't become a permanent stable of the franchise, but how heavily it was being pushed in all Media at the time makes it awkward for the company to keep around now that this prominent feature isn't in the current Games.
Update October 9th 2024: Turns out this Gen of the Anime is currently on a Free App called Happy Kids, it's not as easy to navigate as Tubi is though.