Y'know, I've never read GCS, but rereading other old runs makes me realize how ridiculous it was that they tried to make the bad girls of a Gotham a thing. For most of their appearances - in canon and out - Ivy, Catwoman, and Harley fucking haaaaaaaated each other. Selina, in particular, was manipulated multiple times by Ivy in Hush, Dark Victory, and other stories. Harley and Ivy were at each other's throats when she was still Joker's moll and both women were still allowed to be attracted to men. And then there were the times when Selina was going through a redemption arc and the others weren't, which lead to the designated females on each side having their little gender-permitted fights so you didn't have to feel icky about seeing a guy punch a girl.