Corruption of Shadows
Deo-S can actually pretend to be a revenge killer, force something out, then "lol I gets da screens". Unpredictability lets you BS your way through a lot while Klefki can't force much out and is set up bait.I disagree with Deo-S being considered the best dual screener.
Klefki has Prankster, better type and bulk, so it can actually attempt to switch into resisted attacks and put the screens up mid-game much more easily than Deo-S.
Sure, Magic Coat and Taunt are advantages that can't be overlooked, but Deo-S uses them out of necessity on the dual screen set, since it has no useful resistances to speak of and will attempt to set the screens up against walls rather than offensive threats.