Any of the Arceus you see on GTS and Wonder Trade are hacked, especially the shiny Arceus. The only way to obtain a legit shiny Arceus was if you prebooked tickets to see the 18th Pokemon movie in Japan, and even then there was only a 1/19 chance you would receive a shiny Arceus out of all the other Arceus that were being given out. All of the Arceus came with the Wishing Ribbon attached to them, which prevents them from being traded via GTS or WT; meaning all the ones on GTS and WT had their ribbons removed or were injected into the game without them.