My only real issue with Sceptile ha ability is that it doesn't have the immunity prior to the Mega evolution. What's it supposed to do when it switches into a Rotom-W using Volt Switch and it goes into a Talonflame?
Otherwise the Paralyze immunity and the SpA boost is pretty good.
And Diancie finally looks good, and it may get a new ability too which might make it more viable. God knows I'm thankful because we don't need any more flop Rock types.