Looking at the supporting cast list, I think I'll do a direct comparison to Stephgirl's first however many issues. Up to the Collision crossover. Seeing as Babsgirl just did her first proper crossover, and is at about the same issue, I think this is as good a comparison as we'll get.
Supporting Cast so far:
1.) Jim Freakin' Gordon: Smaller role, somewhat unsurprisingly
2.) Steph's mum. Trying to get over the whole "I was a druggie absentee mum, you were kinda dead" thing. Makes waffles.
3.) Oracle: tech chick and mentor.
4.) Detective Nick Gage : Tall, Dark and Handsome new GCPD Detective who just transferred in. Dark and mysterious past, yet to be elaborated on.
5) Wendy: Got crippled due to being involved with the Titans. Rather angry.
6) Leslie Thompkins. Only in a couple of issues and doesn't do much other than get the plot moving.
Guest Stars for the first year:
3.) Red Robin
4.) Upcoming: Supergirl. And it is awesome.
Villains for the first year:
2.) Roxy Rocket
3.) Dr Phosphorus
4.) That guy who makes replicas of himself but isn't as awesome as Madrox.
6.) Collision - all of RR's LoA foes, for an issue.
7.) Upcoming: Calculator
~7.) Calculator tech zombies, including Huntress, Jim Gordon, Catwoman and Manbat
lolz, nigh copy and paste cast. Of course, BQM probably copied and pasted it too. Parent (rarely more than one), nakama guest visits, one or two characters to tie in civilian life, a cop or two. Works wonders when its done right. Boring and vanilla as cardboard otherwise. From memory, USM and the second half of RR used it too.