i got my light ball by putting a pikachu in front so that its ability static will attract more pikachus (at the trophy garden) and then catching a lot. i didnt even fill up a box and i got two light balls (luck i guess)...if you already tried that, get a pokemon with frisk (such as banette and stanler) and put it in front so you can see if the pikachu is holding a light ball. then switch to a pokemon with thief and use it on the pikachu. Catching wild pikachus is too much work although i did end up getting a lot of oran berries and two light balls. if i can get another light ball, i will trade you one. i am saving the two light balls for other occasions.