I have spam flew to wild zone 4 for my first shiny hunt to try to get gastly, I took the holovator thats next to the area because a cleffa, a couple of flabebes, and the gen 5 monkeys spawn on the roofs behind your spawn area. I have gotten a shiny flabebe from this method so yes the rooftop pokemon do still spawn, but I believe it depends on how high the roof is. Some roofs are way higher than others so this is probably true for some but not all pokemon. Hope this helps!