Fight as Kuroko:
Select versus mode. Press Up, Down, Left, Up, Down, Right + A.

Blood mode:
Highlight the "Exit" selection and press A + B + C + D at the options menu. Alternatively, select Japan as the country on the options screen and exit the menu. Immediately re-enter the options screen and select USA as the country.

Unlimited "POW":
Press Start on controller one and highlight the "Options" selection. Press Start on controller two. The "POW" selection on the options menu may now be set to "Max".