Try buffering airdodges, it may work. I haven't played against a Sheik in a while, so I don't remember.
Still, your best bet is to not get grabbed at high %s. You just have to play like if you were going against ICs, and just hit Sheik with bairs until you get her into the air, then follow her and don't let her go WHILE being mindful of the grabs.
I suggest you should choose stages with nice platforms like Delfino, where they're too high for her tipper to reach you... Maybe Battlefield will work too, you might be able to land and shield on the platforms before her DACUS touches you.