I'm really not a fan of the new 'mega' pokemon, their designs are incredibly bland and half of them look like they're about to feature in a L'Oreal commercial; but one thing that is interesting is that they all seem to have the motifs of Xerneas and Yveltal. Blaziken has X shaped chest hair, Lucario has the same markings as Yveltal, Absol's fur looks vaguely Y shaped, Ampharos has Yveltal's cloudy fur, Mawile's mouths could be held up in and X shape. Maybe the legendaries are involved with their form change? Makes sense considering they're linked to genetics and stuff.