For a new studio that will be focusing on social, mobile platform games. What are roles do we need to fill and how many of each role would be ideal?
It really depends on the kind of game you are making - are you doing procedural content or multiple platforms at once? Budget an extra programmer. Multiplayer? Another half a designer at least. The studio founders (I'm guessing there are between 2 and 4) should sit down and do a rough schedule for the first few games, and then figure out what the headcount should be.
Some positions that are easy to overlook: