No Wind:
While playing, hold R and press Up, Left, Down, Right, Up, Left, Down, Right, X, X.
Unlock Everything:
Start a new game with the name Golf_Gone_Wild.
Change Ball Size:
To increase the size of the ball, hold down the R trigger and press Up, Up, Up, Down. To make the ball smaller hold the R trigger and press Down, Down, Down, Up.
Fifth Outfit:
At the Character Select screen, hold the L trigger and press Y, Y, White, Y, Black, Y.
Distract Opponent:
Start a game with two or more players. While the other person is hitting the ball, press A button to say things to distract them.