Really glad you both enjoyed it! In the end, I'm just glad I had at least one person to move things along so I could actually get the story out there. In the end, that's always my goal, to tell a story no matter the crowd size. I guess in this case I was able to walk the walk. It was fun.
Never really got around to how Yveltal wound up in an adjacent world, but it was something nobody seemed to be aware of. One could deduce it must have had to do with the person who corrupted Xerneas in the first place -- the "greater scope villain" -- who was also behind the hollow Kyurem as well.
Mirage, Negrek already figured this one out, but Weavile -- and the world he came from, along with the origin of this conflict -- is relevant to a campaign I'm actively running, and you're part of. Catastrophe Academy! The world that Yveltal and all of you came from is the same world that my PC, Mirith, is from. You may find more answers there, with time.