so people are currently thinking that trainer customisation will be removed.
^ everything in this picture for Global Link is an NPC character chosen for an avatar, not a customised one.
The screenshots/trailers from XY had various outfits worn by the players. ORAS doesn't have that in those, it's only the main outfits. I think that trainer customising is a Kalos thing cos it's France fashion thingy.
People can pick generic avatars in the Kalos games though. And from the looks of the models from the Mega Evolution teasers, it looks like it'll be easy enough to include customization, especially given May's new default bandana.