To play as them, beat the game with any of characters. When you start a new game, they'll be accessible.
Once you complete the game, you will be able to view the end cinema through the options menu.
Once you have entered the debug menu on the title screen, hold on to 'X' and enter the game, all the way until the domestic affairs screen appears. It does not have to be a continued game, it can be a new game if you want. You will see that you have at least 15 medals, and one of every item, even the DragonForce weapons.
If you hold on to 'X' every time the screen says,''Lord___, Domestic Affairs beckon...'', you should have a fresh supply of items and medals every phase.
To start the debug mode hold L, R, X, and Z then press Down, Down, Up, Down, Down, Left, Left, Left, Up, Down, Right, Right, Right, then start at the press start screen.