If you do it right, you can usmash the nairs every time. If you are on the ground when he's doing them, you can DD around them, but then he's trying to do long range nairs and dairs vs your dash? You can shield those. If you can't hit him OoS comfortably, just WD OoS and enjoy the stage positioning he just gave up. You can also spam bair, if it trade it will usually be in your favor anyway. Try to catch him on his dash back and either shine him or utilt him into oblivion.
Try to overshoot approaches if you want to approach. Run up jab is relatively low commitment, and you can also just CC the first hit of nair. If Falcon's demonstating something close to consistent pivot nair when you try to go in, get in just outside of hit range to do that, ready to dash dance grab/usmash, or shield if necessary. As long as you gained enough ground running after their dash back, you shouldn't have to worry about cornering yourself if you do a retreating aerial OoS after blocking Falcon's stuff (don't forget WD OoS. Approaching with your back to him utilting can also work out fairly well. Better payoff often, but more difficult to safely setup.
