Unlock tournaments:
Enter these codes at the Ring Tournament selection under the Special games option.
A3W5KQA3C Mario Cup
UOUFMPUOM Wario Cup
OF9XFQOFR Peach Cup
M1C2YQM1W Luigi Cup
LA98JRLAR Waluigi Cup
MM55MQMMJ Donkey Kong Cup
ARM6JQARU Blockbuster Cup
N24K8QN2P Bowser Cup
J6M9PQJ6U Nintendo Power Cup
V2UFMPUZM IGN64 Cup
48HWOR482 MarioTennis.com Cup

Hints:
Left-handed character:
When selecting a character, hold L to make them left-handed.

Handicap:
When selecting a character, hold R to make them have handicaps and be more powerful.

Get Shy Guy:
Win the Star Cup/Singles Tournament.

Get Donkey Kong Jr:
Win the Star Cup/Doubles Tournament.

Get the Donkey Kong court:
Win the Mushroom Cup/Singles Tournament with Donkey Kong.

Get the Yoshi and Baby Mario court:
Win the Mushroom Cup/Singles Tournament with Yoshi.

Get the Mario and Luigi court:
Win the Mushroom Cup/Singles Tournament with Mario.

Get the Mario Brothers court 2:
Win all the Doubles Tournament Cups with Mario.

Get the Mario/Luigi Castle court:
Win the Star Cup Doubles and Singles Tournament with Mario.

Get the Wario Brothers court:
Win all the Doubles Tournament Cups with Wario.

Piranha Plant court:
You can only use this court in Piranha Plant Challenge. To get it, complete any court (perfect, all 50 balls) in the Piranha Plant Challenge with any character.

Get the Wario and Waluigi court:
Win the Doubles Star Cup with Wario.

Unlock Special Cups Tournament:
Win all the Tournament Cups with every characters including Shy Guy and Donkey Kong Jr. to unlock the Special Cups, the hardest ones. Press R when selecting a character to access the Special Cups Tournament in the menu.

Bonus difficulty level:
To get a bonus difficulty level in exhibition mode win the planet cup with all sixteen characters.

Get Bowser's brother:
Play with wario a normal game and hold the ball 40 min in the field. If you did it correctly then you can play with the brother of bowser.

Get the Cyriel court:
Play with any caracter on the grass court then hold the ball 1 hour in the game with out make a point (this most be play in one player) if you do correctly then you will get the cyriel court in this court you can make your own settings.