I answered this on FR forum, but will again here. Wish I was getting credit for all these hints-LOL. OK, go to the 5th floor, there's an enclosure with a desk and another attached room with some computers. Go AROUND it,on the edge of the room-fight the trainers-either way you'll fight 2-and it's along the bottom hallway right in the middle of the floor, just pick it up!
Hope this helped, it's pretty easy when you know the location.
I got all the Pokemon a person could dream of, and still working on more. If you need to know the truth, seek it out here, as I am obsessed with answering all the questions I can as best I can. I can verify Event Pokemon, too! My collection keeps growing!