Yeah, I do actually use quite a few original sets. I think some people have borrowed ideas off of me and turned them into popular sets, because I had never heard of anyone using Scarf Landorus-T until after I had used on in the 2013 Spring Friendly.
I don't think they did, considering you didn't have to catch Rayquaza in Emerald. In fact, I don't think you even had to battle it like you did Kyogre and Groudon in RS. My theory is that maybe the Rayquaza story is required to be completed before most of the ORAS post game opens up, and you'll need to catch Rayquaza as a part of that story.
I've always thought maybe it was because Game Freak forgot they can't have a game corner in the European versions, so they gave themselves a week to fix the European version so there would be no game corner. And every other non-European region, including Korea, and Australia are getting ORAS on the 21st.
Yeah, I've already designed optimal sets for all of the new Megas, except Sableye and Latias.
Hey! It's about time you came back to the dark side. Even though you know I'm gone next month...anywho! If you need any help, ask like DK or James or someone. ORAS should be pretty fun, I think xP. If you're finding yourself getting smashed by scrubs..I'll help out ~_~.