Mario Golf: Toadstool Tour (GCN)
Press Z+Start on the title screen, and a special "Contests" option will appear on the bottom of the main menu. Inside are the Hole-in-One Contest and Password Tournament modes.
Enter these in the Password Tournament (unlocked with the code above). "Ohs" and "zeros" are interchangeable.
CEUFPXJ1 - Target Bullseye Tour
BJGQBULZ - Hollywood Video Tour
GGAA241H - Super Mario Open (Mario-Golf.com tournament)
0EKW5G7U - Camp Hyrule Tournament (CampHyrule.com tournament)
2GPL67PN - Bowser Jr.'s Jumbo Tourney
9L3L9KHR - Bowser's Big Blast
ELBUT3PX - Peach's Invitational
Extra power shots
Get a "Nice Shot" with a power shot, and the game won't subtract from your power shot total.
Unlock Star characters
In the Vs. Character mode, challenge the character with a letter (envelope) by them. Beat that character one-on-one to unlock the Star version of that character. If there is no letter, you are using the character that is issuing the challenge -- go back and pick a different character. (Star characters have a longer drive, but his or her "Impact" ability decreases. The four hidden characters are Star players as soon as they are unlocked.)
Collect 50 total Best Badges in Tournament mode to unlock Boo.
Unlock Petey Piranha
In the Side Games mode, complete the Shooting, Approach, and Putting challenges under all difficulty settings to unlock Petey Piranha.
Unlock Shadow Mario
Complete all the holes in Ring Attack mode with any combination of characters.
Unlock Bowser Jr.
Beat the 18 holes option in Birdie Challenge. (Also unlocks One-on, One-putt mode.)
Unlock back 9 holes in Congo Canopy
Beat the front 9 option in Birdie Challenge.
Unlock 18 holes mode in Congo Canopy
Beat the back 9 option in Birdie Challenge.
Unlock One-on, One-putt mode
Beat the 18 holes option in Birdie Challenge. One-on, One-putt will appear in the Side Games mode. (Also unlocks Bowser Jr.)
Unlock back 9 in One-on, One-putt mode
Beat the front 9 option in One-on, One-putt mode.
Unlock 18 holes mode in One-on, One-putt mode
Beat the back 9 option in One-on, One-putt mode.
Unlock Tournament Greens in Congo Canopy
Beat the 18 holes option in One-on, One-putt mode. When selecting Congo Canopy, the setup screen says to press Z to turn the Tournament Greens on/off.
Unlock new courses in Tournament mode
Finish in first place to unlock a new course.
Unlock Star Tournament
Finish in first place in all courses in Tournament mode. "Star Tournament" appears next to the Tournament mode on the Play Mode screen.