I'm just going to say the SDs are either caused by lag or you just playing too risky when fighting offstage. Considering I don't use MK or ZSS I am not sure what advice I can give. As ZSS you can attack with your grab move in the air. It works just like the air grabs of both Links, Lucas, and Samus. ZSS has a long reach with that air grab, so you can stop players trying to approach you. Also, I noticed you did roll at me a few times after getting knocked down. Try not to roll at opponents in general because you will most likely get punished for it 9/10 times. (especially since one of my strategies is to read rolls)