One of the kids responsible for leaving golf balls scattered around the course is hiding in the northern area of the Tiny Tots course.
In-game reset
Press A + B + Select + Start. (Note: If reset occurs during game, you can continue from the saved game file.)
Left-handed golfer
Hold Select and press A to choose a golfer.
Man in Palm Club course
A man is hiding on the far side of the Palm Club putting green. (Note: Find all three hidden characters for 300 points.)
Man in Raven Woods course
A man who says he is on your side is hiding in the western area of the Raven Woods course.
Mushroom power-up locations
On the bookshelf in the room to the right of the Director's room.
On the cabinet in the Club Maker's hut.
To the left of the Peach Castle course entrance.
Peach's Castle course
Defeat all four champions in a match game and finish in first place in all four courses.
Play as Putts
Defeat Putts with a custom character.
Play as Wario
Finish first in the club tournaments and defeat all of the club masters.
Unlimited Hole Retries
To retry a hole from the beginning, before you finish the hole, save the game and exit. When you return to the game, you'll be back at the start of the hole.