Hold Down + Square + L1 + R2 and power on the PlayStation. Continue to hold the buttons until the phrase "Team Neo Blood" disappears. If you entered the code correctly, "Normal Mode" will be replaced with "Hard Mode" and "Hard" will appear above the two player/computer chaos bar.
Play as Bosses (Japanese version)
At the Arc System Works logo, press Down + Square + L1 + R2. Then, release the buttons when the phrase "Team Neo Blood" disappears. Now Testament, Justice, and Baiken may be selected in versus mode.
At the character selection screen, press Square, Triangle, Circle, or X.