@Just
Jiggs should rarely, if ever, be shielding. You know what happens if her shield is broken. Right?
All aerials are able to be used, pound is pretty good and eats half a shield. She's able to cross up her opponents as well, which helps her not be shieldgrabbed. Pound cross up into bair. Retreat away. Rising dair cross up, bair. She's able to weave in and out. It's helpful.
Fair cancels out certain projectiles (same with nair), and with her many jumps and low crouch she can avoid basically every projectile in the game. (Go watch ChuDat's Kirby and you'll get an idea how it's done, it's basically done the same way with Jiggs)
We're talking lower tiers here however. The low tiers actually have a problem hitting a good jiggs. So dying at a low % doesn't make that huge of a difference.
GL simply airdodging through Jiggle's juggle game. Again, you already mentioned you know nothing about the character.
Jigglypuff actually has a reliable KO option. All of Link's and Ganon's moves are so slow they shouldn't be landing anyways. You getting dair'd or something? Ganon has.....well... uair I guess? and Link has........... well... er.... ............ hell, my only combo video ever was for my Link, I mained him for several months, and I still can't think of a reliable KO move.... his KO moves require your opponent messing up or a good read.
The tl;dr of this
Jigglypuff mains need to play gayer, bait more, and learn how to land rests. I only ever play her in friendlies (Snakeeeee mainnn in tourney).
Except for her stupidly hard high tier matchups, she's decent. Better then Ganon who has what.... 1 even matchup.. vs Falcon?