Hyper Street Fighter 2 Cheats

Unlock Akuma:
Pick the GAME SPEED then select the SUPER X character type on the character screen. Then highlight the following characters in order: Ryu for two seconds, T. Hawk for two seconds, Guile for two seconds, Cammy for two seconds, and Ryu again for two seconds. Immediately press Start followed by Three Punches (you can set then to one button, such as L1). The time that the pointer highlights a character must be exactly two seconds.
User Cheat by Old_School_Gamer

Or you can get to Akuma easier, you will need a second controller and good fighting skills. Go into arcade mode. Select your best fighter. When the first fight has started, press Start on controller two before the Cpu hits you. On controller two, select the fighter you are up against. Then, have player one defeat player two with a perfect score. Once defeated, you will move onto the next round. Repeat this tactic until you reach M. Bison, getting perfect scores every time. When you reach M. Bison, the usual "Round 1 Fight" will happen, but you will not fight M. Bison himself. Instead, you will fight a much harder Akuma.
User Cheat by Old_School_Gamer

Additional difficulty settings:
After finishing the game under the normal difficulty setting you will unlock the easy and hard difficulty settings.