SRD; Monsters; Monster Types said:Proficient with whatever type of armor (light, medium, or heavy) it is described as wearing, as well as all lighter types. Undead not indicated as wearing armor are not proficient with armor. Undead are proficient with shields if they are proficient with any form of armor.
frankthedm said:As it happens, Bugbear zombies seem to keep sheild prof.
frankthedm said:the template does not give armor profs and strips away the feats that might have given it.
I imagine you'd use similar logic to how they retain weapon proficiencies:phindar said:Not to get too picayune, but what's the logic there? If I dig up a bunch of skeletons, animate them and they don't have armor on, I can't put it on them later because they won't be proficient. If I dig them up, dress them in armor and then animate them, they will be proficient. Or, if they aren't proficient in armor, I put them in armor, then they are described as being in armor, and therefore are proficient.