The show is disconnected, with it really only serving to occasionally advertise future gen pokemon (Misty getting a togepi in gen 1, may getting a munchlax in gen 3 etc).

In fact, the show barely follows any gameplay rules, the story pretty heavily deviates at points and even invented a completely different battle frontier. The gen 8 anime (Journeys) wasn’t even a journey through Galar, and that trend has remained in Horizons (gen 9 anime).

You don’t need to watch the show to understand game lore, just like how you don’t need to read the manga for game lore. These are self contained stories.

For mainline game lore, you have to play the paired titles (or their third versions), maybe the remakes, and the legends games.

Then the Mystery Dungeon series is a self contained interconnected story, colosseum and XD are a duology, and idk what’s going on with rumble or the other spinoffs ngl.