first against sliq i wouldve just went back to story, or maybe battlefield, u have much less mobility without platforms, jiggs isnt really effected, and it makes it easier for her to edgeguard.
u got gayed the first game cuz u tried to grab, i dont go for grabs so much against jiggs unless they are free, but there is a trick to safeguard yourself against crouch rest. just dont do running jc grabs and u can space the standing grab so that u are far enough away that she cant reach u with rest in time and will have to nair. its situational but something to mess around with, ex. u can walk in grab, or run in wavedash straight down (dash cancels dont eliminate momentum) grab, and mix this up with downtilts spaced really really well.
the rest of the time im not in her face im either shooting needles off plats or spacing bairs on her approach. work on spacing needles better off platforms and shooting more of them i.e u dont always have to follow up the needle with a run off fair, instead run off fastfall dj back and shoot another one and jus wait for a clear opening, or shoot a needle run off waveland back and chill for a second. jiggs has no answer to needles and bairs.
for your edgegame, shinostall more against aggressive edgeguarders like jiggs, she is lookin for low percent cheap kos, this will give u space. last time i played sliq i killed him through the roof with an upb stall, and he ran into it alot.
another ledge "trick" i use is the games ledge jump and hold back, they try to back air u, miss, and u double jump back at em with fair.