Why did Rhydon's Lightning Rod fail?

Question

I was in an X and Y online free battle using Rhydon with the Lightning Rod ability and Mega Banette against a Thunderus and an Electivire, but while Banette used Phantom Force and Rhydon used Swords Dance, Electivire used Discharge, but Banette still took the damage and got paralyzed. When Banette fainted I sent out Altaria, but she took damage too. Electivire had Motor Drive, but I don't know about Thunderus. Lightning Rod sucks in ALL Electric attacks on the battle field, but it still didn't work. Can anyone explain why? I'll provide more information if necessary, and I even saved the battle video.

Answer 1

Generation IV
Lightningrod now also forces all single-target Electric-type moves used by allies to strike the Pokémon with this Ability. Electric-type moves used by allies will never miss the Pokémon with this Ability.
Lightningrod cannot redirect Electric-type Judgment or Natural Gift.
If another Pokémon becomes the center of attention, Electric-type moves will be directed to it instead of the Pokémon with Lightningrod.
Generation V and VI
Along with its previous effects, Lightning Rod also gives the Pokémon immunity to all Electric-type moves, and raises the Pokémon's Special Attack by one stage whenever they are hit by one. This effect will not activate if the Pokémon is protected from the Electric-type move.
If the Pokémon is Ground-type, its type-granted immunity to damaging Electric-type moves and Electric-type Thunder Wave takes precedence over the Ability so the Pokémon's Special Attack will not be raised, unless it is holding a Ring Target.
Lightning Rod can now redirect Electric-type Hidden Power, Judgment, and Natural Gift.
If a Pokémon with Lightning Rod is holding a Cell Battery, Lightning Rod absorbs the move so the Cell Battery's effect is not triggered.
In Triple Battles, Lightning Rod cannot redirect Electric-type moves if the Pokémon is out of range.

Bulbapedia on Lightningrod

Discharge is not a single-target move (i.e. it targets multiple Pokemon at once), so Lightningrod failed to activate to divert the damage. Simple as that.