I laugh at how barely any one is interested in the theory of two different OOO's and are mostly interested in comparing pokemon types, probably because Decade's name was mentioned.
Word of advice, next time when mentioning AU's, don't mention Decade, because AU's have been a part of the franchise, LONG before Decade. I.E Agito, Ryuki, Faiz, Blade, Hibiki (to an extent), Kabuto, Den O (with Climax Deka, maybe), and Kiva all had AU movies. Therefore meaning, WAY before Decade we already had two different worlds of the same rider around. Those just simply had the same person being the rider.
I'd like Movie War Core's OOO portion to be canon to OOO since W's was canon to W and I'd like to believe W and OOO exist in the same world, but there are too many inconsistencies with the OOO portion so it's very much easy to simply say it's just an OOO Movie AU.