Super Gouki
To use 'Super' Gouki, highlight Gouki, then press and HOLD Start, then press A, B, X, or Y to select him.
Play As Super Vega
At the character selection screen, put the cursor on Vega, press and hold the START button, then press A, B, L, R, X or Y to select 'Super' Vega. This changes his pre-battle pose, and it adds an enormous aura around your hard punch, and most importantly, it gives you the Super Psycho Crusher. However, you cannot select a fighting style, and Super Vega is only available in the Arcade, VS and Training Modes.
Final Battle Vs. Shin Gouki
Select final battle, and go through what you would normally do as you were fighting Vega. Right after the 'select speed' screen press and hold all buttons (excluding start button) Gouki's portrait should appear and you'll now fight against him.
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! Good luck!
Get EX-Vega(Shin-Bison):
Beat the game with a World Tour character that you've entered into the game. Then beat arcade mode with a difficulty of 8 and without continue the game. Once you got that, you can use EX-Vega in arcade, vs., and in training mode by highlight Vega and hold on to start and any button to select him.
Get The 6th ISM Plus:
Raise a character to level 32 in World Tour mode. When you reach the last stage (in Japan), either win or lose; it doesn't matter as long as you get to the ending credits. Save the game and your character should now have an asterisk (*) next to him/her. Go back and beat the arcade mode with that character without continuing to receive the 6th ISM-Plus, "Guts". This raises all of your stats slightly.
Play As Shin Gouki
At the character select screen, select Gouki, hold START, and press an action button to choose Shin Gouki. Shin Gouki moves faster, has a double air fireball (4x in V-ism when a combo is active!), and juggles opponents more easily.
Play As Super Akuma
At the character select screen, highlight Akuma, hold start, and press A.