[@Skwint] Right, I should clarify that. I say mob as a general term here. In true ork fashion the mob you're part of isn't going to be so rigidly structured as saying, everyone must be equipped with 'X'

You aren't restricted to just slugga or shoota boyz, though you are more than welcome to pick either of those. Basically the main restriction is that no one is going to be the equivalent of an elite unit, like a nob, mega nob or a big mek. You can still be a mek if you want, just a regular (little) mek, painboy, burna, etc For the most part we're looking at basic types of boyz. But you still have options.