Not sure if this shiny Groudon is legit. I got it from the GTS. It's in a Master Ball, with the right ability and stuff. It came from the Unova region apparently, but the next part makes me think it's hacked. Perfect IVs in every stat. It's awesome, yes, but I need to know if it's hacked or not.
As of right now, you can't get Groudon in Unova, so its obviously hacked. Also, the only 6iv legendaries you can get are from events, like the Moonblast Shiny Jirachi.
You can only get Groudon in Johto and Hoenn.
Hopefully this answers your question
Hope I helped!