Board Thread:Questions and Answers/@comment-34111279-20180612140550/@comment-4339465-20180612173902

If you mean when adding them to a character's outfits page, there's no special format, it's the same as the others in the order of the outfits in-game, except with the "how to acquire" message being "Unlock for 500 Yumemcoins". (Unless it differs, but I think most are 500 at least?)

Other than that, having them named reasonably and in .png is great.