1st & 2nd camp Hyrule Park
Go to code select by pressing Z-R-A when clubhouse is highlighed and in cheat select type 0EQ561G2. Do the same thing as the first code, but put in the code 5VW689O6.
Successfully defeat a character in versus mode to unlock them as a playable character.
Koopa Cup course tournament
On the "Code Entry" screen enter KPXWN9N3 to play a tournament at the Koopa Cup course.
To play as Metal Mario get all 108 birdie badges in Tournament mode.
To access the password screen, highlight the fourth menu option on the main menu, then press and hold Z followed by R and A. The password inserter will appear in the next menu.
Play as Maple
To open the character Maple earn 50 birdie badges in Tournement mode. She has a 245 yard drive but she drives it completely straight.
Restart a Hole
Pause the game on the hole that you would like to restart. Choose "Save and Suit" and save the game. Now go to "Continue" and resume the game from the tee of the hole that you were on.