It would be the same case as a Goldeen/Seaking getting hit with an electric move when it has LightingRod. It would absorb it and get a Special Attack Boost.
>Gives an immunity to Electric-type attacks and, if the wielder is hit by an Electric-type attack, grants a Special Attack boost to the Pokemon. In double battles, it redirects Electric attacks towards the Lightningrod Pokemon, unless the move hits multiple Pokemon. If Hidden Power is Electric-type, it will be redirected and absorbed as well. If Follow Me is being used, an Electric-type move will hit the Follow Me user instead. Electric type Judgment hits through Lightningrod. There is no out of battle effect.