Explnaing how the material textures are made:

The ***_ID.png texture dictates the location of colors
The ***_RCM_1P.png texture dictates what color is used (RCM_2P for the player 2 alternate color palette)
The ***_MASK.png texture is used to add details and shading to the final material texture

The transparency of the ID coresponds to what color on the palette is used, where the areas of lower opacity use colors from further left on the palette (see example 1). Extract the red channel of the mask texture, use the resulting greyscale as the alpha channel of a black layer placed over the previously created color layout (see example 2)