There was about a page worth of pictures with puffy_pants and shorts and I went ahead and tagged those with puffy shorts, puffy_shorts, but I'm pretty sure there are more out there.
The main question would be if it should be different from puffy_pants or implicate it.
I guess we could use it as a tag alias or perhaps make a distinction between the ribbed and non-ribbed versions? Or maybe something more arabian styled?
I do notice the pumpkin_pants do seem to be more, pumpkiny and that there is some inconsistency with a pumpkin shaped/styled dress.
imo I like the term puffy_shorts more, seems more universal.
That's actually taking pumpkin_pants quite literally. Pumpkin_pants is in reference to a particular type of clothing, and going by google/wikipedia are called trunk hose and slops (difference is where they end in relation to the knee), especially those that had a paned or pansied style (those with vertical stripes). Their appearance was similar to that of a pumpkin, so ended up getting commonly called "pumpkin" pants. I believe that that then got broadened out and refer to the general shape of the pants now.
Also your first example is actually kind of mislabeled, post #1306428 isn't even pants.
Minor edit: The Japanese seem to refer to this similar type clothing as カボチャパンツ (Pumpkin Pants). Can be found in use on pixiv as a tag.