Thanks for posting this! I was looking all over the save blocks trying to find the skin tone value and completely missed PlayerAppearance > SkinColor.
One thing I'm curious about: has anyone tested whether there are additional valid values beyond the ones shown in the image? Sometimes Game Freak leaves unused customization options in the data, so I'm wondering if there are any hidden skin tones or if values outside the known range just default back to one of the standard options.
Either way, this is really helpful information for anyone editing their save. Thanks for sharing your findings!