As a SoCal netplayer and person who goes against a LOT of sheiks (Kira, sherigami, SacaSuMoto, etc.) You need to mixup your superior movement against sheik. Sheik's movement is pretty trashy compared to falcon. Don't get grabbed, ever. CP to Dreamland or FoD, and keep Sheik in the air. Sheik horrible when she's being juggled, and uair is great for that. It's a bad MU, but its a possible one.
For edguarding her, it's relatively easy. Knock her off and grab ledge, and just react to where she goes. Depending on where she is, one sheik poofs from her up-b you should either A)Roll off ledge to cover ledge option and react if she goes onto stage or B) Ledge hop once she poofs, this is hoping on the fact she doesn't go to ledge. Her Up-B has a LOT of landing lag, and can easily be punished with knee/dair. Also once she's on the ledge, don't challenge her if they know how to shino/refresh invincible frames. Let them come to you.