Okay so I know this might be a hard to answer question but if you answer both ill give you best answer and up vote :D
That house is only accessable with the long-gone-by Darkrai event. IT is no longer accessable unless you use AR or some other means of hacking. ( It requires the member card)
That house was only accessable through an event. If you got the event ticket, you can go in, and then get Darkrai
Hope this helps!