Smeargle-Sketch
Sketcher of Smeargles
I'm going to assume that Arceus either feels threatened by the appearance of foreign settlements on its home soil or that it wants its plates back.Bird Keeper Toby came up with an interesting theory. The idea is that Arceus is making the Pokemon mad because of something the humans did long ago, like the swordsman who killed a bunch of Pokemon, or it's trying to kill Cyllene because of what Cyrus attempts to do in the future.