I'm in the same boat as Kurona. Mega Scept is mediocre, at best, with that ability. I would have preferred something more niche, exclusive... useful. Everyone goes on about T.Wave/Electric immunity and possible S.ATK boosts, but its like those very same people forget you have to Mega Evolve first and basically tip your hand to your opponent that you got Mega Sceptile, be careful with Electric moves!
Aside from that, giving it Lightning Rod would be no different than giving Zard X Flash Fire... going from x4 resistance to immunity isn't a huge step up.
Mega Scept falls into the category of Mega Evos that don't change much, for me. Tyranitar, Abomosnow, Scizor, etc. as opposed to true game changers like Manectric, Mawile, Venusaur, Banette and Charizard.
As for Swampert... could take others by surprise, sure, but he needs bulk. Either way, though, at least he got something somewhat interesting, and not an immunity in place of a x4 resistance.
On the topic of the Battle Frontier, it better be in OR/AS. Aside from a few key Pokemon, its really the only good thing about Hoenn/Gen III. After completing the boring narrative, venturing through the unmemorable Hoenn region and defeating the poorly designed Gym Leaders/E4 (minus Phoebe), it was a nice reward to spend so many hours overcoming the challenges of the Battle Frontier.