Bowser: Transfer 81 Birdie Badges over From Toadstool Tour
Luigi: Transfer EXP from Mario Golf: Toadstool Tour.
Waluigi: Get 27 Best Badges in Mario Golf: Toadstool Tour then link up.
Wario: Transfer 54 Birdie Badges over From Toadstool Tour
Azalea: Beat her in match play
Gene: Beat his team in match play
Grace: Beat her team in match play
Joe: Beat him in match play
Kid: Beat him in match play
Putts: Beat his team in match play
Sherry: Beat her in match play
Tiny: Beat his team in match play
1-Up: Complete Putting Practice on Expert
1-Up: Complete Shot Practice on Expert
1-Up: Complete Approach Practice on Expert
Custom Ticket A: Search the club maker's cabinet.
Custom Ticket B: Knock out the Bloopers in the Palms Practice Area.
Custom Ticket C: Knock Out The Pokey in the Dunes Practice Area
Custom Ticket D: After beating the Mushroom Cup on singles and doubles, go to the Links Course driving range and talk to Kid

1up mushrooms make you level up 1 level. Drinks make your distance increase and Club cards allow you to get new clubs from the club maker.

Drink 1: As you are given control of your golfer after the conversation where you are paired with your partner in the story game head over the walkway to the right go in the lower door. Follow the path and you will be on top of the castle. Go left you should find stairs, look for a barrel and walk up to it and press A.

Drink 2: In the marion training ground look for klepto. Hit the bird to save koopa, he swims over and give you the drink.

At the time that you would press A(2) to hit topspin, press A then B. You will have super topspin.
At the time that you would press B(2) to hit backspin, press B then A. You will have super backspin.

Enter the clearing between the Coo Coo Course and the Links Clubhouse. Check the big tree in the middle of the field for the Power Up Mushroom.

In Peach's Castle, when Peach asks you if you want to start the tournament, answer "No". Then, walk to the left, all the way to the far back of the castle. You will find a barrel containing a Level Up Mushroom.