Lightning rod! My Rhyhorn kicks ass...
LightningRod, because like others have said, it draws in Electrical-Attacks in multibattles (to usually an Electric or Ground-type), powers up SP.ATK, and Pikachu has it.
*Switch Out previous Poke, Switch In Pikachu*
??? used -ElectricAttack- on Pikachu!
Pikachu absorbed the attack with LightningRod!
Pikachu's SP.ATK rose!
Pikachu used Volt Change + STAB + LightBall + LR Boost.
Pikachu returned to Player.
Blind Switch next round
At least, that's what it's like in my mind at the moment :P.