go to the underground after you get the explorer kit and dig it up.
Chat with our AI personalities
You can find them underwater and if you catch a luvdisc they may be holding a heart scale.
you have to use hm rock smash on rocks to find them.
OK... so there is this guy in solaceon town that gives you a heart scale and 3 pokeballs. U can also find them under ground. ;D
There's a man in Fallabur town who will re-teach a Pokemon a move for a heart scale. But you must find a heart scale, they are in several places on the map but are mostly in or near water.
Heart Scales can be purchased in the Pokeathlon shop for 1000P