Boombots (PSX)

Unlock all characters and levels:
At the BoomBot selection screen, press Square, Square, Square, Square, Circle, Circle, Circle, Circle, Square, Square, Square, Square, Select, Select, Select.

Cheat mode:
At the BoomBot selection screen, press Square, Circle, Circle, Square, Circle, Circle, Square, Circle, Circle, Square, Circle, Circle, Select, Select, Select to enable cheat mode. Then, enter one of the following codes to activate the corresponding cheat function:

One-hit kills CPU opponent:
Pause the game and press Circle + Square + Triangle.

CPU opponent has 100 health less:
Pause the game and press Circle + Square.