Okay, all you have to do is go on Advance-Map by LU-HO and you can get it here on PC or you can just google it (make sure you got the latest one or the 1.92 version, which is the one I still use), make a patch of grass, then add wild pokemon (there's a tab that says wild pokemon) and then you add the pokemon you modified. Oh! And welcome to PC! Have a nice stay and vm/pm me if you need anything! :)