It's not even close to rare, sorry. It's probably just an advertisement for a website that gives out hacked Pokemon (like machamps.com, for example), and it's supposed to make you use their hacking services. It's a scam, and the Pokemon are 100% hacked -- but hey, you get a free, technically legit Master Ball out of the deal.
Just remember that if it's way too good to be true (which this is), then it's fake.
