Would it be at all possible to make the effect of a player being frozen/golden transparent and be able to see the regular textures under it? I did a little test to make the frozen effect transparent and it doesn't show the model's main textures under it, it just becomes transparent. It would be really cool to see a frozen player that is not just solid ice, sorta like how the players are frozen in The Winglet's "Overwatch vs. TF2" at 3 minutes, 44 seconds.
Technically, yes, but it's not at all worth the effort. You would have to edit all player models to not have any UV mapping that overlays with each other, create a combined texture for it (meaning, yes, the body and head and eye textures of all classes in one single texture), and make both the player materials and the frozen/golden materials load that texture and/or a re-coloured variant of it.
Both the Golden and Frozen models use a plain, single color texture to override the textures that's shared for each class. So not without combining every single model UV into one texture (or only playermodels if you don't care about cosmetics looking wack)