Could be that, or have a case of two suicide squad teams 'working' together until the second squad learns how to disable their brain bombs with help from someone like the Thinker and sabotage Harley's team.
Wait Ratcatcher is a woman? But in comics is a man. No, WAIT!!! SHE'S RATCATCHER 2 Ok! THAT'S GOOD. And she was trained by the Original RATCATCHER. THAT'S AWESOME!!!