Password screen:
Highlight the "Clubhouse" option at the main menu, then press Z + R + A or A + L + R . Note: This does not work in the PAL version of the game.

Nintendo Power tournament:
Enter KPXWN9N3 as a password to play a tournament at Toad Highlands. Note: The shadow with the "?" indicates that any character can be selected. Another password will be displayed after completing the tournament. The ten character password is not actually a password for the game, but is for a promotion in Nintendo Power magazine.

Nintendo Power Summer Scramble tournament:
Enter FJQ49LJA as a password to play a Speed Golf event at Mario's Star course with Donkey Kong. The lowest time wins. Another password will be displayed after completing the tournament.

Left-handed golfer:
Hold L or Z while selecting a golfer at the character selection screen.

Alternate costumes:
Hold C-Left, C-Right, C-Up, or C-Down while selecting a golfer at the character selection screen.

Compliments:
Press any direction on the D-Pad during your opponent's turn.

Easier CPU player:
Compliment your opponent as much as possible after their shot and he or she will be easier to defeat. For example, if the CPU player gets a perfect shot, press Up to say "Nice Shot!" at the same time that the game announces it.

First Camp Hyrule Cup:
Enter 0EQ561G2 as a password. Note: Donkey Kong must be selected as a golfer. The password contains the number zero as a character.

Second Camp Hyrule Cup:
Enter 5VW689O6 as a password. Note: Plum must be selected as a golfer. The password contains the letter "O".

Taunts:
Press C-Left, C-Right, C-Up, or C-Down during your opponent's turn.

One player Skins mode:
Choose the player-controlled character, then hold R while selecting more characters to set them under CPU control. Select a play mode and choose to play Skins.

Play as Luigi:
Defeat Luigi in get character mode.

Play as Yoshi:
Unlock Luigi as a selectable golfer, then defeat Yoshi in get character mode.

Play as Sonny:
Unlock Yoshi as a selectable golfer, then defeat Sonny in get character mode.

Play as Wario:
Unlock Sonny as a selectable golfer, then defeat Wario in get character mode.

Play as Metal Mario:
Get all 108 birdie badges in tournament mode. Metal Mario hits 285 yards and a high draw. He is still the best golfer in the game, with Bowser only being able to hit 280 yards.

Play as Gold Mario:
Unlock Metal Mario and highlight that character at the selection screen. Then, hold C-Left and press A.

Play as last four characters:
The last four characters on the bottom row can only be unlocked by using the Game Boy Color Mario Golf game and the Game Boy Transfer Pak that allows data to be shared between the two games. The four characters are Joe, Kid, Sherry, and Azalea.

Play as Harry:
Unlock Wario as a selectable golfer, then defeat Harry in get character mode.

Play as Mario:
Unlock Harry as a selectable golfer, then defeat Mario in get character mode.

Play as Bowser:
Unlock Mario as a selectable golfer, then defeat Bowser in get character mode.

Play as Donkey Kong:
Get thirty stars in ring mode.

Play as Maple:
Get 50 birdie badges in tournament mode.

Mario theme song:
Unlock all the players in get player mode and allow the credits to complete. Once the credits are done, the Mario theme song will start and you will receive a reward.

Alternate ending sequence:
Successfully complete the game with a character to feature him or her during the ending sequence.

Alternate course creature:
An alternate creature will jump out of the hole if you can sink a putt for par or better with the 200 ft putting range. Even if the putt is only 10 feet, if you put it on the 200 range and sink the putt for par or better a small mushroom creature will jump out of the hole instead of a gopher.

Play at night:
Select get character mode and enter "Sudden Death" to play the same course at night.

Perfect power shot bonus:
When a power shot is made and the ball is hit perfectly, a bonus animation such as a fireball (with a 1D club) or rainbow (with a 4W club) will appear. Additionally, your golfer will not lose a power shot. For a spinning fireball, use Mario to get a perfect power shot. For thunder, use Bowser, get a perfect power shot -- you will hear a big boom. For lightning, use Wario to get a perfect power shot.

Easier wins:
To defeat characters easier or to maintain your status without having to start completely over, save the game on bad drives. Then, do that course without restarting the competition again.

Push the ball:
Repeatedly tap Z or A when the ball lands on the ground to move it a little bit further. Note: Hold Z to quickly advance the ball to where it would normally stop for a faster game.

Abort swing:
Press B immediately after pressing A to start a swing.

Mario Star course:
Score at least 2200 points after unlocking five other courses in the game.

Replay hole:
Pause game play on the hole to be replayed. Use the "Save And Quit" option to save the game. Then, select "Continue" to tee off from the same hole.

Alternate introduction sequence:
Unlock Donkey Kong as a player. Then, wait for the introduction sequence to appear a second time. The first time it appears, the sequence shows Yoshi carrying Baby Mario. Remain there and allow it to appear a second time to see Donkey Kong carrying Baby Mario.