Ok here's the other three.....
Shadow Mario: Beat every Ring Shot Course with someone. Note; You must use the same character for all of them or it will not save your progress.
Petey Pirahna: Complete the putting, Driving, and Approach side games on all levels.
Bowser Jr.: Beat all 18 holes in the Birdie challenge. Note: In order to do this, you need to unlock the all 18 Holes option. To do this, beat the first 9 holes, which unlocks the back nine. Beat the back nine to unlock all 18.
That's all! Glad to be of help Dr. Wario!
Only a fool scoffs at the laws of Ushido. *Takes out Katana* The might of righteousness will overcome the wrath of evil. *Eats slice of Pizza* My cause is worthy. Meow! I am the Samurai Pizza Cat!