If you're tired of earning gear the old fashioned way, input this code anytime while playing to unlock all weapons:

hold L2 + R2 and input RIGHT, RIGHT, DOWN, UP, LEFT, LEFT

You must win 12 Medals, 19390 Points, 85 PPH.
You must win 8 Medals, 8430 Points, and 65 PPH.
You must win 5 Medals, 3700 Points, 50 PPH.
Collect 11 Medals, 16070 Points, 80 PPH
You must collect 3 Medals, 1820 Points, 40 PPH.
You must collect 70 Points and 15 PPH.
You must collect 7 Medals, 6560 Points, 60 PPH.