When I was in Copenhagen for Go Fest, I very much loved the Pikachu with the LEGO background and was lucky enough to get a perfect (hundo) but did not end up with a Shiny. This event is taking place from August 3rd until September 30th, with a Gym and a Stop at select LEGO locations within participating countries. You only get two tries at getting the Shiny with the background, per location, per day. I made my way to our two closest, which are Westfield and Bluewater shopping centre, finding the LEGO store using the map locations. Spinning the stop will give you a stamp; however, this stamp rally does say it's on until February 3rd.