I am not sure. i think Sonic possily has an advantage but the way I ru my Sonic is generally not very good fr the matchup.
TEKNI WHERE ARE YOU!?
Well, if you can't reach Tenki for some reason, then, Kojin is the next logical choice...
simple explanation: wall of pain is a pain in the ***. it makes sonic have to slow down and attempt to punish inbetween attacks. I play jiggs on a semi regular basis, and the player has a decent understanding of Wall of pain strategy.
The are some unkonwns though. if the jiggs is really good at spacing, it can get hard for sonic to capitolize, because the air game, is almost out of the quesiton. If sonic can grab her, then set up offense from okizeme, that is a good foundation to beat her. because she then has to get back in the air. you control the ground in this matchup. Rollout is usually a risky move, so u won't see it as much. When I usually get that Dthrow on a jiggs, then I can get most aggressive. Sometimes I like to hypehn smash at them once i got a good idea of thier rythem and catch them as the rise or fall from an attack. then it becomes easier to get in for me after some of those because then they have to either empty jump or anticipate my attack/airdodge, btu because of my speed i can mindgame either, or fake an approach altogether. And if Im unsure, just run away from her range.
Both of characters are really good at recovery, though i think sonic is better. you're also heavier, and Jiggs Smashes can be punished by sonic. If you're patient you'll eventually force jiggs to make a mistake. that's my thoughts.