So, I did a bit of science... If you somehow manage to lose a battle in the OR/AS demo, it aparently counts as a Game Over, kicking you back to what's pretty much the start of the demo and removing all Exp you had gained after that point. It does give you a bit of unique text, though. Note that losing a battle pretty much requires you to throw the battle on purpose, so yeah. I'm half surprised they even thought of the option at all, let alone threw in an otherwise unviewable bit of text.