i work for nintendo and i also completed the game....all you have to do is new game ur game..!!!!!!!!!!!!!SAVE!!!!!!!!!(if ur happy with ur file right now then dont new game it but u wont get arceus), then look at the tv, og out to talk to ur rival, go to lake valor then lose to the wild pokemon...go to sangem town,then save there......then keep saving in every city until you reach jubilife...you only have to save 3 times too.! WARNING DO NOT SAVE IN ROUTES. THIS ONLY WORKS IF YOU NEW GAME IT THOUGH... then go to the cave, go north, west, south, north, east, north, west, then save then roam around the cave then arceus will appear...this is a top secret secret so dont tlel anyopne else.