Super Street Fighter 2 X

Fight as Gouki/Akuma:
Highlight Ryu press LP + MP + HP + Start at the character selection screen.
Information in this section was contributed by Joe Endy.

Fight against Gouki/Akuma:
In single player mode, get at least three perfects without using any continues. Gouki/Akuma will appear instead of Vega/M. Bison.

Ex options:
Highlight the "Options" selection on the main screen, then hold L and press A.

DIP switch menu:
Successfully complete the game with all the characters, using their Super Turbo versions and the Super versions. This requires completing the game thirty two times. Once this accomplished, hold Y and press Start. This allows you to enter a DIP switch menu to tweak the game.
Information in this section was contributed by Brian Creighton.

Ten and Shin Gouki:
Unlock the DIP switch menu, then go to these numbers: On the third row starting from the left, change numbers 9 and 10 from 0 (which is disabled) to 1 (which is enabled). The codes are for Super Street Fighter 2 versions (with no super bars). Select the character with Jab then input the directional sequence for that particular character. Up and down motions include: E. Honda, Chun Li, Guile, Dhalsim, Cammy, Sagat, Vega (M.Bison in North America), and Dee Jay. Left and right motions include: Ryu, Ken, Blanka, Zangief, T- Hawk, M. Bison (Balrog in North America), Fei Long, and Balrog (Vega in North America). Once this has been done, you can enable Shin Gouki and Ten Gouki by pressing Start and 3K for Shin, and Start Short Punch, Fierce Punch, Forward Kick, Round House Kick. Ten Gouki has the Shun Goku Satsu which is performed by pressing Jab, Jab, Analog-stick Forward, Short Kick, Fierce Punch.
Information in this section was contributed by Brian Creighton.

Mark opponents as defeated:
Select arcade mode. Once your next opponent appears, press Start on controller two and choose that character. Use controller one to win the match against that character, and the game will mark him or her as defeated CPU fighter. Note: This cannot be done in the final match.