ok it is quite complicated and it might take u a long time like me but its in route 209 which is south of solaceon. ride your bike side to and up and down really really violent and vigorously. and itll slow down the loading line comprehension and it wont be able too comprehend all the data
So go and try it, if you find discoveries post them here. only 1 one person has gotten Darkrai or Shaymin. To get Arceus you go to spear pillar. u find the loading line and you "oh i forgot one important thing you can only holepunch by using your bike!" ride your bike til you get a white void, i forget the rest but ill post it later
check this stuff out. Found it on IGN(a trustworthy site)
to get darkrai u need to tweak near the canalave city hotel ya kno the one thats locked well tweak near there, which is extremely hard, and a void with appear, step into it and youll here the souns of the hotel house, but no one has tweaked there so much for the whole hotel to be there.
to get shaymin you need to go to route 224. and right where the sand starts is the loading line