If anyone wins the BG, KF MU it's Killer Frost. I co-main both characters and theory fight constantly which of the duo would fair better versus one another. For me, it really boiled down to who has the better post slide guessing game. BG's B12 is too slow to combat Frost's D1~slide or MB F3; the same is true for BG's B2U3 and throw. BG's D1~redemption or D1~cartwheel is BG 's only was to start pressure, and even these option are unsafe thanks to parry, or null and void thanks to backdash. In addition, Batgirls's favorite wakeup is parried, leaving batgirl to either commit to her unsafe options or guess correctly like most of the cast. Also, jumping back in footsie range to try and catch a slide is something a lot of characters have implemented, but is something that I have adapted to simply by delaying slide until they are already headed back to the ground, causing them to get hit by slide as they are in recovery. Now, I am not saying that KF beats BG by a huge margin as BG does have her damage in the corner and meterless fortex, rather, just insisting that it is definitely not in BG's favor.