The movie also proves that if an AU changes too much of the original story, it is likely to end up worse. ORAS' story is better than RSE's, but that has nothing to do with the Mega Evolution angle. The presentation simply explained the villains' motivations better... and Zinnia added some spice, although I have a problem with the Delta Episode as a whole. Basically, the name of the game is additions rather than blatant changes to existing elements. An AU only works if the writer has a deep idea that can only be delivered via a multiverse, as I do. But none of the Pokemon media have any meaningful interaction between universes.