Well if you feel the AI is cheating, cheat right back.
Infinite weapons - The controls must be set to the "Classic" option for this code to work. While playing a game, hold L1 + R1 + L2 + R2 and quickly press Up, X, Left, Circle. If you entered the code correctly, a message will appear
Infinite health and turbo - The controls must be set to the "Classic" option for this code to work. While playing a game, hold L1 + L2 + R1 + R2 and quickly press Right, Left, Down, Up. If you entered the code correctly, the words "Invulnerability On" will appear