It was really obnoxious in XY and SM. SM because the dex was filled with Kantomons and that Alola forms were only Kanto, while XY had pandering for no reason. At least the Alola games, annoying with the Kanto pandering as they were, actually used it within the story. XY's Kanto pandering was just there because they could. There was no reason for Santalune Forest to be a copy of Viridian's except for nostalgia. I think I like USUM much more just because the Pokemon additions make Alola's dex feel less Kanto pandery as a lot of them come from Gens 5 and 6, and make the games feel more rounded as a result.
LGPE is just the icing on the cake and I have no interest in it whatsoever. After 2 generations with Kanto pandering, it feels redundant. I'd love to see a game where there are mons from every generation besides 1, but they'll never do it. Wouldn't be as bad if it weren't the same mons every time. At least Alola had some that are barely seen in games, like Parasect, Hypno, and Primeape, which haven't been in a regional dex since Johto.
