Honestly, all I would really like in G6 is a UNIQUE fire-type combination. I mean seriously, ENOUGH with the fire/fighting types! Blaziken was BA with this combo, I was content with Infernape, but Emboar just makes it overused.
I would also like to see a diversion from the normal starter choices, like what was speculated about G4. You now, with the rumor that the starters would be of the Fighting/Dark/Psychic types? That would be cool ^^ Like what about a Flying/Fighting/Rock selection?
Or the ability to start with a dragon type<.< >.>