I am trying to help my nephew. Apparently since I can't find it on my guide but all his pokemon got knocked out when he battled N and when he tried to go back the guy at the pokemon center said he couldn't go back right now. What does that mean since that never happened to me before.
I found it out but it was the one you battle him at his castle after you battle the 4 elite four members. My nephew couldn't figure out how to go back to his castle but told him to check the poke center for a team plasma guy to do it and he did it.