You were definitely right about the brawl comparison. Brawl is so match up based, player have to adapt their playstyle for different characters to exploit their opponents weaknesses and hide their own. I see a lot of people claiming they struggle with a supposedly advantaged match up because "they don't have the right style". In that case, deal with it. In brawl, even MK players need to adapt their play for Snake and IC (can't hit Snake to much or get grenade countered, have to air camp IC to not get grabbed).
Jiggs has a ridiculous punishment game, which everyone knows about. She also excels at bating moves, so everything falls into place for her quite nicely. Now, all you can control is getting baited. Against jiggs, never try and play a risk:reward ratio game, as a single error gets punished by death (or a decent chunk of them anyway. Play as infuriatingly safely as possible and don't et jiggs bait you into doing something stupid. Choke and go for a kill move and you may get punished for it. Just because they are at kill percents doesn't mean you have to kill them. Just let kills come, but don't get hit.
TL;DR
A lot of theory-core, but jiggs can't beat out everything. Safety seems the more reasonable solution to a character based on punishing.