Ban Suicune

I'm sure this question has been answered in this thread already, but there isn't a search function for individual replies within this post. Where do you go after you beat the psychic gym? The dudes at that station thing north of it are #sleep. I saw talk of the black market or w.e and i actually spoke to the team aqua leader about it and he told me it was on 7th street below reborn city or something, but unless the whole game is Reborn city, I haven't been there yet. So where the heck do i go.