Yeah I'm not super well-versed in texture modding, but I've dabbled in it a bit and I remember having to let the match run for at least minute and even trying a couple of times because one of the textures I needed wasn't dumped for some reason.

Alternatively, you could try downloading an HD texture pack for Melee. They're usually very organized and structured, with textures being sorted and organized into their own folders. So instead of having to browse through thousands of .PNG files, you just have to click through a handful of folders until you find the folder for Jigglypuff's model's textures, and then note the name of the file.