Jiggs can be uthrow - uaired at anywhere between 0-85ish...aside from SDI the first hit, in reference to what scotu is saying, its called spacing, it is possible for a jiggs to rest out of the combo at the low percents but fox's uair far outranges the hitbox of the jigglypuffs rest, it doesnt matter the her rest is 1 frame if she isnt in range.
My brother mains jiggs so this is by far my best matchup, and in terms of if the jiggs is at a low percent i wouldnt even go for an uair, i would go for a bair, same amout of damage and more potential to combo, even the you can't combo out if the jiggs is good, shes too high, but she will be lower after a back air then after an up air, therefore she has less time to re-space herself and gain her composure.
I would only start going for upairs at about 40 percent, stage depening, DI aside on yoshis if you get an uthrow at 45 the uair will kill...if its about 40 and the jiggs DI's up by accident you can get the kill that way too...i find the only reason a jigglypuff or any character will DI an upthrow uair up is because they go to jump out of the combo, and use up on the control stick to jump, ruining theyre DI.
Also on an unrelated note, i find instead of a shine immediately after a SHFFL nair approach, do a turn around utilt, into an uair.. 0-40 = better then 0-15 from a shine. If youre good you can have two combos and get a kill...nair-utilt-uair...space for a grab uthrow-uair.
Patient foxes win against jigglypuff....stay away from the edge and make her approach you and you will get way better in this match-up...theres a reason this is one of the top 3 worst match-ups for jigglypuff... you get used to DI the uthrows quickly and youre fine for the uthrow rest that everyone thinks is amazing.
Get setting the DI to being as quickly set as say a quick ground tech. And you will **** jiggypuffs....except mango/king...theyre good.
And chase them in the air I guess.
