What are now exactly the delta episodes? Like delta sapphire?

Question

I don't get it (and the game either...)
You can install it on your ORAS game right?

Answer 1

No it is included in the game. It is pretty much a post-E4 mission.

Answer 2

The Delta Episodes are a series of missions you do after you complete the main game.
Rayquaza and Deoxys are obtainable at the end of the episodes.