Just a small question: how to lose to the last boss? When the balancer joins I cannot make the hero surrender and when their both HP reaches zero I get directly a Game Over screen. I unlocked everything else, also the hidden ending.
Note to whoever plays the game:
In the Great Prison area is a subarea with slaves, one of them begs to be released, his cell has a broken wall at the back. You can simply open the door and use the pickax to create a hole. That leads out of bounds and you can walk to the right, go down a ladder to find the Ultimate medal nullifying status abnormalities and increasing player stats to 256. It will be better to find it during the game, not after completing it

. (it does not offer the strongest attack, though, but you practically no longer need it)
PS: Seemingly you need to make bad decisions once during play-through, even after getting the good end you can do Yuna in the hospital and lie to Yuna in the cell afterward, get all the scenes with the female bosses and rewind time (20 times maybe). Now after beating the final boss again I got the choice of good end or bad end as a route.