I forgot the site I found this on but since technology keeps improving, it will get harder and harder to find working wifi for it. Such as heartgold, soul silver, and even platium. If you are playing Pokemon gen 5 and up ( including x and y) and your wifi or the hotspot you are using is up to date, than you should have no problem. Vice versa for heartgold ect if your wifi is not up to date.
I hope this helped!