To get inf rare candies go to battle tower (pokemon emerald) put a rare candy on a pokemon in your pc go to the closest lady click double battle then open lvl when it's saving turn off your gba turn it back on it will say the game has been curupted then continu go back to the pc and take the rare candy off of the pokemon go to your bag and you'll see 2 rare candies
P.S. save before you go to pc first time