(Temporarily) Changing player skins?

My latest mod idea involves giving players special powers/immunities/weaknesses based on drops from monsters (think monster meat from Final Fantasy Legend/SaGa). I think I've got the general concept down on how to implement it, but I'd like to be able to override the players' skins while they're under the effects of these changes. I've done googling and looking through tutorials, but I'm still not sure how, or even if it's possible to do this, or if what the launcher says goes. A pointer would be much appreciated.

If it's not possible, I have a second fallback idea of using particle effects like potions have, but definitely like the original idea better. Besides being cooler, it would require less memorization of what each particle effect indicates which monster skillset.