Just wondering. If they are equal, then I'm using a Light Ball.
Actually, Light Ball is a lot better than the Life Orb on Pikachu.
Light Ball = doubles power of Special and Phyical attacks of Pikachu
Life Orb = increases damage by 30% at a cost 1/10 of HP each hit
Souces: http://www.serebii.net/itemdex/lightball.shtml , http://www.serebii.net/itemdex/lifeorb.shtml