Alien stadium and team
Enter "ATEMYBUIK" as a code at the cheat menu. If you entered the code correctly, the phrase "Let the abductions begin" will appear. Now a stadium called Alienapolis will appear at the end of the stadium selection screen. When you select this stadium, the second team will be the "Abductors". The players will remain the same except for their apperance.

Baseball trails
Enter "GRTBLSFDST" as a code at the cheat menu. Alternatively, press B, Left, Up, Right, Down, B, A, Left(2) during the game.

Giant baseball
Enter "BBNSTRDS" as a code at the cheat menu. Alternatively, press Up, Right, A, Left(2), B, Up, Left(2) during the game.

Two dimensional players
Enter "PRPPAPLYR" as a code at the cheat menu. Alternatively, press Up, Right, A, Right, A, Down(2), Up(2), Down during the game.

Fat and thin players
Enter "ABBTNCSTLO" as a code at the cheat menu. Alternatively, press A, Left(2), Right, Up, B, Right during the game.

Big heads, feet, and bat
Enter "GOTHELIUM" as a code at the cheat menu. Alternatively, press Left, A, Right, Down, B, A, Left(2) during the game.

Big heads and feet
Enter "BIGHELIUM" as a code at the cheat menu.

Credits
At the title screen, press R, A, Z, R, C Right, A, B to enable a credits option.

Programmer messages
At the title screen, press C-Up, R, B(2).