Kingdom Hearts II/Abilities

Drive/Form Abilities
And to let you know:
 * Valor Form is available when you upgrade your clothes
 * Wisdom Form is obtained by clearing Timeless River
 * Master Form is obtained by talking to The King before the second visit to Space Paranoids.
 * Final Form is made available by reaching the "Memory's Skyscraper" and seeing the cutscene with Roxas. This will unlock the chance for Final Form to appear when changing into any other Drive Form. It is easily obtained by going to the "Fragment Crossing" (2nd room of TWTNW) and changing into a Drive form. If you turn to the form you chose, go to the "Alley to between" (1st room of TWTNW) and you will have your Drive gauge full. Go back to the "Fragment Crossing" and try again. Also Final Form will be available under Command: Drive > Final, after you've once succesfully activated the Final Form

It is well worth equipping the abilities