Well, let me tell you this: I got a hacked Machamp over wifi that seemed perfectly legit. Until one day, whenever I finally got it to level 100, I realized it had max IV's in all stats and atleast 550 EV's put into it. Sure enough, after I battled someone and saved a battle video, the Battle Video said, "There is a problem with some of the Pokemon in this battle," or something like that. So, that is when I had proof it was hacked. I eventually released it. (Not after I breeder it with some Dittos, lol.)
So, have a battle with it and save the Battle Video. If you can watch the Video, it's not hacked (badly).