This announcement states that a few Pokemon (Gastly, Drowzee, Zubat, and their evolutions) will have a hugely boosted spawn rate this week.
However, when I was out last night and today in two different locations, I saw only two Zubat, but a large number of Meowth, Cubone, and even Marowak. There must be other Pokemon that have been boosted but are not on the above list. If so, is that recorded somewhere? I'm in the southeast US if region ends up playing a factor.