FIFA Street Cheats

Maximum speed, power, tackling, tricks, etc.:
Hold L + Y and press Left(3), Up, Down(2).

Mini-players:
Pause your game, then hold L + Y and press Up, Left, Down(2), Right, Down, Up, Left.

Normal size players:
Pause your game, then hold L + Y and press Right(2), Up, Down(2), Left, Right, Left.

All apparel and footwear:
Hold L + Y and press Right(2), Left, Up(3), Down, Left at the main menu.

All apparel:
Hold L + Y and press Up(2), Left, Up(3), Down, Left at the main menu.  

Normal size players:
Pause the game, then hold L + Y and press Right(2), Up, Down(2), Left, Right, Left.

Easy goals:
When you are at the bottom left or right of the pitch, cross to a nearby player and head it. You will score about 95% of the time and about 60% of the time you will do a classy goal.

FIFA Street Official Website

FIFA Street Review - GameSpot

FIFA Street Review - IGN