Pocket Fighter:

Play as Akuma- place your character select 
cursor on Ryu and press left

Play as Dan- place the character select 
cursor on ken and press right

X-men vs. Street Fighter:

Play as Apocalypse- to play him in vs mode 
beat the game at the hardes level. next 
enter two player vs mode highlight akuma 
in the top row. finally press and hold select 
for at least 5 seconds then press any punch button

Tekken 3:

Record your Combos- first select 
the practice mode and and pick a
 character. then go to the free 
style screen and press L1 + L2 +
 R1 + R2 + circle.youll know its
 correct when the following comes
 up on the bottom of the screen PLAY
(SELECT)REC(Down + SELECT). to record
 your combo hit down and select. To
 play back your combo hit select.

Theme Hospital:

Level Passwords- 
Level 2- x,o,s,t,t,o,s,x
Level 3- o,o,t,s,x,t,o,t
Level 4- s,t,o,s,x,x,t,o
Level 5- o,t,s,o,x,t,o,s
Level 6- s,t,s,o,x,s,x,o
Level 7- s,t,t,o,x,s,t,o
Level 8- x,t,s,o,t,o,s,x

Thunder Truck Ralley:

Increased Traction- at the main 
menu press left,L1,R2,R1,left,
R2,R2,R2. if entered correctly
you will hear a burp noise.

Tennis Arena:

Hidden Characters and Hidden Court-
 At the smart dog logo quickly press 
up,down,left,right,start. 
if entered correctly you will hear a cheer.

WCW Nitro:

Voodoo Mode- at the player select screen 
press L1 seven times,l2+select. you will
 hear a sound if entered correctly.