Hold R1,L1,Y,B,A,X and press white all at the same time.
If you do so you will be at lvl (10) with 45 skill points and $500,000
*YA I NO THATS ALLOT OF CASH*

(this only works on two player)Once you have got really far in the game but are bored of your current character start a new game , And import the good character from you're other game , then drop your good stuff and let the second player pick it up. Then import your other character and voila , good stuff.