To unlock all the secret chars and arenas:
At the BoomBot selection screen, press
Square(4), Circle(4), Square(4), Select(3)
To enter the Cheat Mode:
At the BoomBot selection screen, press
Square, Circle(2), Square, Circle(2), Square, Circle(2), Square, Circle(2), Select(3)
Now you can use those while playing, whenever you want:
One-hit kills CPU opponent:
Pause the game and press Circle + Square + Triangle (together)
CPU opponent has 100 health less
Pause the game and press Circle + Square (together)
If you at first do the One-hit kill cheat and then the 100-less one, your enemy will drop like a fly at once.. almost like magic...