Mob Textures

I'm not sure if this is possible i can't really find any information on it. 
but lets say i wanted to spawn a regular skeleton but have it have the texture of wither skeleton.  (without resource packs)
or spawn  wither skeleton but have it have the texture of say a warden ( i understand they don't line up and there will be visual issues)
what i want to know is if this is possible with out the use of a resource pack as the actual assets are on the client.