>>46680473It's mostly told to you, but there are some lore elements you have to go out of your way to find. The plates have lore written on them, and solaceon ruins has a bit of lore as well, there's a hiker in oreburgh mine that tells you about arceus if you have the plates (I think), and some random NPCs add flavor text here and there. The regis also have a bit of lore that isn't part of the story. The mythicals + cresselia also have lore elements that aren't part of the main story. Also the old chateau.
