There will be heavier instances of the lines featured in Sinnoh (the ones that got evolutions added, or were added entirely for Gen IV). Those would be Misdreavus, Duskull, Drifloon, Spiritomb and Rotom; otherwise, the swarms will surely contain others from different locations as well, doing their ghost thing and generally being places they should not be, just not at as high a concentration - Sableye included, of course!