@magalor42druid multiclass monk, unarmored defense apply to wildshape? ex wolf 13 nat ac +its dex mod and druid wis mod?
not in my opinion – natural armor counts as armor. use higher of base 10 + mods or form AC
— Mike Mearls (@mikemearls) May 25, 2015
Ummm.. however, while it counts as armor, you are NOT wearing it. Which is also an operative part of the phrasing. Another bad Sage Advice
I would have to agree with Mearls here. The most important part of the phrasing in Unarmored Defense is that your Armor class becomes 10 + Dex + Wis. This calculation ignores whatever your AC would be normally so the AC in the beast statblock is considered an alternate calculation. This falls in line with racial Natural Armors, such as Tortle or Loxodon. As a Tortle Monk, you get higher of 17 AC, or whatever Unarmored Defense totals out to be.
AC bonuses that would add into AC like normal would add into Unarmored Defense as usual, so if a beast had an ability that says it gets a bonus to AC this would be the only way it could be added to Unarmored Defense. I am not aware of any beasts that declare this though.
Should you have a pair of bracers of defense however, which state that you gain a +2 bonus while not wearing armor or shield you could apply that bonus to your beast shape natural armor. However you will need to convince your DM that the bracers will be practical for your beast form to use, as per the rules of wild shape.