Alright, we all know Xerneas can learn Horn Leech, and I just recently got a Japanese one from the GTS with some random luck. Now, i'm going to be straight with you all, I like moves that restore HP, (especially when paired with a Big Root) such as Drain Punch, Oblivion Wing, (THIS move is why I favor Yveltal over Xerneas) etc.
So, how could one make Horn Leech work fora Legendary that's even more locked-on to Special attacks?