Cheat List:
During gameplay, press START and enter any of these codes:

Sword Upgrade - Hold L BUTTON + R BUTTON, X, B, X, Y, Y, B, X, B

Complete Current Mission - Hold R BUTTON, B, B, B, X, Release R BUTTON, Hold L BUTTON, Y, Y, Release L BUTTON, Hold R BUTTON, B, B

Big Heads - Hold R BUTTON, Y, Y, Y, Y, Release R BUTTON, Hold L BUTTON, Y, Y, Hold R BUTTON + L BUTTON, Y, X, Y

Unlock Battle Arena:
To Unlock Battle Arena, earn all the Grades, Then you should get the Master Grade. The Battle Arena Will be open at Robot Beach.