Arceus-Ghost @ Spooky Plate
Evs: 252 SpA / 4 Def / 252 Spe
This thing is such a notorious stall breaker and lure its not even funny. The only things that can normally wall Calm Mind Ghost Arceus are Chansey and Blissey, and thanks to Substitute, they get turned into setup bait. Substitute has other notable merits too. It lets you heavily dent a revenge-killer, used burned Ferrothorn as setup bait, while also allowing you to abuse what is likely the most common spinner in the game, Sub Split Forretress. That and Substitute is helpful for taking a hit since the chances of Focus Miss hitting is less then 0. It may look like its outclassed by Giratina-O's Sub CM set, but its lack of a Dragon-typing making it tank Dragon Tails really is enough to distinguish it. That and Focus Blast is actually helpful 0_0, it can do stuff like OHKO Tyranitar whereas Giratina-O's Aura Sphere cannot accomplish the same feat. Oh and Ditto has nothing on this / can't revenge it :D.