Yes, I also a little bit confused why he have weak armor ability as hidden ability? But, in my opinion, that was just Game Freak Choice. Game freak just wanna to add more Pokemon with the ability of weak armor. Like do yo know Mega Punch and Mega Kick move? That was "punching" and "kicking" move and, it supposed to be fighting type move. But, the both we're Normal??? The answer is: That Was Game Freak Choice everyone keep saying that. Then, I got more and more confused. Because, many moves or ability doesn't match the shape of the Pokemon's body or the others..... And, I believed yes, that was the answer =========> That Was Game Freak Choice!!!