It's way late, but after watching seasons 1 and 2 of MPL: FiS (created by Lauren Faust who also worked on Powerpuff Girls) I realized more fully what Bleedman and BeeAre were doing in the 'April Foals' page. It should be obvious when Buttercup has a Cutey Mark (man, are the CMC going to be pissed if they see that!) It also should be obvious as Buttercup is a Unicorn, Blossom is a Pegasus (although she was flying at the time already), and Bubbles is an Earth Pony. Bell is probably also an Earth Pony. For some reason, I would have liked to see a follow-up comic. A shame, in a way, it was an April Foals joke.
I think Buttercup is better suited to being an Earth Pony or Pegusus, being similar to both Applejack and Rainbow Dash. Blossom is similar to Twilight, so she would make a good Unicorn. Bubbles is similar in some ways to Fluttershy, and in other ways to Pinkie Pie, so she can be whatever Buttercup is not. As she faces all three, Bell can be a winged unicorn, although not of the same stature as the series's two physical gods.