Pokémon Model Ripping Project

[THElectrolith]

Hi, everyone. I've been trying to actually get the models correctly textured in 3DS Max. Still, I don't understand how to texture eyes, mouths and body at the same time. I tried with separate materials, but nothing to do.. I've seen some of you could do it, like that super cool Solgaleo with the starry texture on his head, and I just would like to understand how you do that. Thanks in advance