How to Unlock Bowser Jr. in Mario Golf: Toadstool Tour - wikiHow

Bowser's favorite Koopaling is golfing for the first time! Believe it or not, he practices golfing on his dad's private course. He's putting his skills to the test in Mario Golf: Toadstool Tour. You must unlock him to play as him, so read on to find out how.
STEPS

1

GO TO THE "BIRDIE CHALLENGE IN ONE-PLAYER MODE." Select "Side Games" and press "Birdie Challenge."

2

GET A BIRDIE ON THE FRONT 9 HOLES, THE BACK 9 HOLES, AND ALL 18 HOLES.
A message and picture should come up saying you have unlocked Bowser Jr. Congratulations!
TIPS
Use a good character with good Impact and Control.
Use a Star character if you have unlocked one.