This reminds me of Ryu vs Dhalsim in SF... Just block and know when to push forward. If you just keep dashing and jumping carelessly you WILL get blown up. Try timing your air dashes after you block the wave of bullshit she throws at you.
Once you get in 5a range, just bully her with it and your B attacks to keep her from using lows that go under your A.
This match is in Mitsu's favor, only reason Yukiko can pull out a win is if you get inpatient and start running into shit
Teddie, on the other hand....