Free Step Dodge

Is that the back back punch combo?

Yea that one.

As a pro Kasumi player, I wouldn't use it often. It's best to use when the opponent misses a hold and you knew it was going to miss, or to stop an advancing opponent from hitting you when you back up. However, I feel the input is who pay, and it hardly ever works when I use it. Whatever you do, avoid pressing PPPPP as a combo after it, because it's predictable and will get you held.