Mario Golf: Toadstool Tour

Boo appearance
Watch the intro and when Bowser is chasing the Wario Bros. you will see the hidden character Boo playing with Birdo.
(Thanks to Metal Sonic 5000)

Camp Hyrule Tournament
Go to the special tournaments option (hold Z and Start at the title screen) and go to password tournaments. Enter 0EKW5G7U as the password and viola! You've got the Camp Hyrule Tournament!.
(Thanks to Chunky Kong12345)

Hidden Characters appearance
(even if you haven't unlocked all characters this cheat will still work)
Complete Tournament Mode. During the credits, look and you will see the 4 hidden characters.
(Thanks to Metal Sonic 5000)

Peach Open Code
At the Title Screen, hold Z and press Start. Then at the special tournaments page enter the code ELBUT3PX.
(Thanks to worrom@hotmail.com)

Star Tournament
Beat the original Tournament Mode to unlock Star Tournament (which is basically hard mode).
(Thanks to Metal Sonic 5000)

Super Mario Open Code
At the Title Screen, hold Z and press start. Go to the Special Contests icon and then choose Password Tournament. Enter this code: GGAA241H and enjoy.
(Thanks to Chunky Kong12345)

Target Tour Tournament
Hold Z and press START at the title screen and a new option comes up. Go to password tournament. Then enter CEUFPXJ1 as the password and get the Target Tour Tournament
(Thanks to Chunky Kong12345)

Unlock Birdie Challenge Back Nine and all 18 holes
Beat the front nine in the Birdie Challenge to unlock the back nine (Beat the back nine to get all 18 Holes in one run).
(Thanks to Chunky Kong12345)

Unlock Blooper Bay
Win Sands Classic in Tournament Mode.
(Thanks to worrom@hotmail.com)

Unlock Boo
Get 50 Best Badges to unlock this hidden character.
(Thanks to Metal Sonic 5000)

Unlock Bowser Badlands
Win Peach's Invitational in Tournament Mode.
(Thanks to worrom@hotmail.com)

Unlock Bowser Jr.
You unlock Bowser Jr. (Yes, it's Bowser Jr. not Baby Bowser) by completing the Front Nine, the Back Nine, and then doing all 18 holes of Birdie Challenge.
(Thanks to Metal Sonic 5000)

Unlock Bowser Jr.'s Jumbo Tourney
Enter: 2GPL67PN
(Thanks to lshanno3@yahoo.com)

Unlock Cheep Cheep Falls
Place 1st in the Lakitu Valley Tournament. Beat Cheep Cheep Falls Tournament to unlock Drifting Sands.
(Thanks to Metal Sonic 5000)

Unlock Drifting Sands
Beat Cheep Cheep Falls Tournament
(Thanks to Metal Sonic 5000)

Unlock Hollywood Video Tour
Hold Z at start screen, press start. Go to the new special event option, select the password tournament, then enter BJGQBULZ to get the HV Tour.
(Thanks to Chunky Kong12345)

Unlock Peach’s Castle Grounds
Win Blooper Open in Tournament Mode.
(Thanks to worrom@hotmail.com)

Unlock Petey Piranha
Beat the Shooting, Approaching, and, Putting practice side games on all three levels to play as Petey Piranha.
(Thanks to Metal Sonic 5000)

Unlock Shadow Mario
Beat Ring Attack with one character or more.
(Thanks to Metal Sonic 5000, Chunky Kong12345)

Unlock SP mode
Hold Z and press start at the title screen to unlock both Hole-in-one Challenge and password Tournament.
(Thanks to Metal Sonic 5000)

Unlock Star Character
Play challenge match and defeat the player with the letter and you will unlock the improved version of the character you just battled.
(Thanks to Metal Sonic 5000)