Items are not transferrable from gen 4, otherwise I would have traded it already~
I guess I need to find some wild Pikachus but idk where they are o.O
edit: yeah, the page says it's impossible to get wild Pikachus.
I'm pretty sure there has to be a way though...
I NEED TO GO TO JAPAN.Light Ball is not available ingame in Generation V, nor is the Item available in the Dream World. Only two Events in Generation V allows you to get it, and both were only in Japan in In-Life Events (Held by a Pikachu). Pokemon transfered from Generation IV cannot be holding Items, so those Events, or trading with someone who went to those Events, are currently the only legitimate ways of obtaining a Light Ball in Generation V.
Sorry.