BlazBlue Continuum Shift Question! How do you beat and what happens when you beat Mu-12

I’m going through the complete BlazBlue series of games. I’m on the second Continuum Shift Extend for PC. Under certain conditions I get to a boss named Mu-12 after the last boss (Hazama). However I can never beat her. So my question is what happens if I do? I have tried to find something online (like a video) but there is nothing.

On a related note can I use the following trick to retry the battle?

  1. Use a second controller when I’m about to loose to start a PvP battle.
  2. Win it
  3. I can now retry the Mu12 battle.

Is this accurate?