Play as Super Vega - Select arcade, training, or versus mode. Then at the character selection screen, highlight Vega, hold Start and press A.
Play as Super Akuma - At the character select screen, highlight Akuma, hold Start, and press A.
Tougher World Tour
Score more than 3,000,000 points in WorldTour mode. After the final battles against Juli/Juni and Shin Vega, you'll get to "GOKUENTOU" island where you'll face your toughest battles yet.