Borders: Bubblegum, Iron, Serenity, Simple
Backgrounds: Backlight Horizontal and Vertical, Lensflare, Stone
These skins were in the original release of Tattoo, but are now separate to make updates quicker (and because now you can have more skins).
TattooSkins don't do anything without Tattoo or Tattoo Minimap. They will load, because there is no "dependency". Since the skins can work on both Tattoo and Tattoo Minimap, they cannot be dependent upon either one.