I hate slates with 4 good options, but here we go.
Protean Goodra obviously with its strong special defense and diverse move pool an assault vest will be good, very effective at coming in on any special attacks, but I was thinking of using this as a purely offensive buff, and trying a specs set. You come in, force the switch, and pound the new guy with a STAB draco meteor or fire blast. I say that less to convince people it'll be effective and more to show that there's more than one way this can be used, even with that meh speed stat.
Give klefki a way to kill itself? Hell yes! Unfortunately I've already voted for one prankster and absolutely refuse to allow another.
I like Lightning Rod Emoleon, but with goodra being such a strong option, I'll need some convincing. The penguin looks very comparable to Heatran, but heatran has a huge advantage of being one of the only fire types that isn't total garbage defensively, Empoleon on the other hand has plenty of water competition.
Levitate Doublade is certainly better than no guard, but it still seems like knock off, shadow ball, and fire blast bait. As good as that typing is, it was always the mind games that made Aegislash so good, and of the three bulky attackers in this slate, this is probably my last choice, simply because we already know what affect this would have on the meta if it were to be great, and everyone decided they didn't like it already.
Yes but it also acts as a full Rotom-W stop and one who is able to act as an offensive mon (unlike Lanturn) :D