I've been waiting for Giritina-O for too long. The tier IMO needs an offensive Ghost-type outside of LameGar that can counteract some Super-powerful Extremespeed sweepers out there. And just as Imanalt mentioned, he is a great Pokemon to use against Imposters! Frankly, I believe that if we are going to allow Darmanitan-Z into the tier as a form, then on the same grounds we should allow Arceus. Darmanitan-Z essentially goes through the same check as an Arceus form does (ie. an ability check) but with the additional condition of holding on to a type of item. Now I can understand if the game can not keep a permaform of an Arceus-type without the plate would be grounds for a "ban", but I think the addition of "usable" Arceus-formes would really spice up the metagame. To be frank, I don't think the Arceus sprite thing will really be game changing for the metagame as your advertise it. Already having your Ability Slot + Item Slot (which is more important in BH than in other metas) nailed down means the bluff won't add nearly enough viability to typed Arceuses to make them common enough for the mechanic to really come into play.