Let's say I am in a Double Battle with a Tapu Koko and a Manectric with Lightning Rod on the field. Now, my Tapu Koko uses Thunderbolt to attack my opponent. Will my Manectric's Lightning Rod activate?
Yes. If any Pokemon on the battlefield, apart form the Pokemon that has Lightning Rod, uses an Electric type move, the Electric type move will be redirected to the Pokemon that has Lightning Rod, and its sp. atk will be raised. Source: Experience