If you're talking about getting onto the edge against ZSS, here's general advice when someone is trying to edgeplay you.
You have 6 major options, getting onto the edge.
-Ledge Jump (just press jump while on edge)
-Ledge Roll (just press shield while on edge)
-Ledge getup (press <- or ->, whichever is onto the edge.) (0-99%)
-Ledge getup (press <- or ->, whichever is onto the edge.) (100+%) (this one is longer and has more edge invincibility, mostly used for edgeguards.
-Ledge attack (press A on the edge) (0-99%), small-ish range attack.
-Ledge attack (press A on the edge) (100%+), small-ish range attack, takes longer.
You can mix these up to try to get onto the edge, without being predicted. Then comes planking & ledgehops. Gnw has a great planking game, probably top 3 in the game. You can possibly just wait unitl the ZSS gets bored or something, it works lol. OR if that isn't working, try ledgehop up b. This is probably the best option, since the ZSS won't uair high enough since you'll be very high.
Also ZSS in general, just don't try to play close combat with her, otherwise you'll lose. Approach her with spaced bairs diagonally, and do NOT get mindgamed into her dsmash, otherwise you'll take like 40%+ that Game and Watch really can't afford to take.