MLB '99

An Out Despite a Hit
Throw the pitch so the hitter hits it, then throw the ball to second base. When the basemen catches it, move away so the base is covered by the other teammate. Move close to the base and press Triangle. This will make the ball go high into the air. While the ball is in the air, move the outfielder to the ball before it hits the ground. If he catches it, it's an out.
Super Player
At the Player Creation screen or during Spring Training, enter Scott Murray or any other Development Team name.
Baseball Bloopers FMV Sequence
Enter the Start Menu and allow the game demo to run. Watch it until the FMV sequence appears, about half way through the first inning.
Easier Hits
While at bat, hold Down and press Power.
Start a Fight
Have you pitcher hit the batter on purpose, then press X, X, X.

----------------------------------------------------------------
 MLB 2000

Automatic Home Run
In the batter's box, use the power swing, then press Up + Left + L2 + R1 + X when the ball is thrown.
Super Player
As a Player Name at the Player Creation screen, enter Scott Murray, or any other Development Team Name.
Big Heads
At the Start/Options screen, press R1 + R2 + X. If done correctly, you will hear a sound.

----------------------------------------------------------------
 MLB 2001

Automatic Home Run
While batting, press X, Triangle, Circle, X, X, X.
Super Player
At the Player Creation screen, enter any of the Development Team names located in the back of the instruction manual.
Spring training stadiums
At the stadium selection screen in exhibition mode, move to the left or right until the spring training stadiums appear.

----------------------------------------------------------------
 MLB Pennant Race

Always Hit Home Runs
Go to create player, and name your player, First: B Last: B. Then trade him, and when he is up to bat, his name will be Mark Meniham and he will always hit home runs.
Super Player
Go to create player and select a pitcher slot. Type in REX in the first name and BACA in the last name. He can now hit 600 foot homers and pitch up to 140mph.

----------------------------------------------------------------
 Mobile Suit Gundam: Perfect One Year War

Bonus Options
At the Bandai Logo, press Up, Triangle, Left, Square, Down, X, Right, Circle, then hold L1 + R1. If done correctly, a sound will be heard. Release L1 + R1 when the Title screen appears. Press L1 + L2 + R1 + R2 to access Addition Mode.
CHOOSE LEVEL
At the animation before the title page, hold L2 + R1 + SELECT + LEFT.