You are playing Lambda. A lot of her defense is not being in the wrong spot in the first place. In other words, instead of trying to run up and AA them a lot of the times it is better to just airdash back or backdash so you have room again. But if they really are getting in your face, you should be able to AA them. 6A can be beaten by Hakumen if he spaces it right, but only if you do it too early. You basically want to get in real deep and 6A only then.
If you're farther away though you can just 6D them in the face for airdashing at you.