turtle tyrant 4914 3870 8238 [Fire: Magmar, Pyroar, Ninetales] No.16514125 Report It's easier to get a heart scale this gen than ever before, not sure why you're having difficulty.
Fish with an Old Rod on the Southern Coast of Cyllage, 100% of the pokemon that show up are luvdisc.
Forget compound eyes, it's a waste of time switching your pokemon back and forth.
Just thief every luvdisc. I'd say I get the heart scale at least 30% of the time.
MAKE ABSOLUTELY SURE YOU MOVE THE STOLEN HEART SCALE TO YOUR BAG, OR YOU WON'T BE ABLE TO STEAL ANYTHING. Gotta keep that item slot open for the stealing to occur. I assume this is your problem.
I can steal 4 heart scales in 10 minutes, easily.