If you want to know all the rare candies look at this list.

At Trick Master house(first challenge)

Route 114 in the waterfall at the top

Route 110. Pick the low road. When your in the low road use surf when you find a island(I don't mean new mauville)you'll pokeball

Route 108. Go to the bottom part and go on a land press A on them(the others have nothing.)

Route 120. you'll find a tree that is cutable (I don't mean the raining part one)at the end you press A

Ocean current. this one is not a lie just because it's very hard to get it

A pokemon with a Pick Up ability(it's more easier depending how high the level is)