Mario Power Tennis - Platform: Gamecube

Paratroopa:
-----------
Win all three Normal Cup tournaments in doubles mode.

Petey Piranha:
--------------
Win the Special Cup Fire and Thunder tournaments in doubles mode.

Star Cup:
---------
To unlock the Star Cup beat the 3 tournaments of the Normal Cup.

Star for character:
-------------------
Win all three Normal Cup tournaments with a character to unlock his or her star version.

Wiggler:
--------
Beat normal flower cup in doubles, to unlock Wiggler (Defense).

Alternate Yoshi's defensive power shot color:
---------------------------------------------
Win the Flower Cup tournaments in doubles mode.

Balloon Panic mini-game:
------------------------
Win the Flower Cup tournaments in singles mode.

Bowser court:
-------------
Win the Special Cup Fire tournament in singles mode.

Coin Collectors mini-game:
--------------------------
Win the Mushroom Cup tournaments in singles mode.

Event Games:
------------
When you get to the main menu, push 'B' to go back to the 'Press start' 
screen, then hold 'Z' and then press 'Start' or 'A' and then Event games will be unlocked.

Flat shot:
----------
When charging up a shot, press A+B to do a really high shot.

Fly Guy:
--------
Win all three Normal Cup tournaments in singles mode.

Hana-Chan:
----------
Win the Special Cup Fire and Thunder tournaments in singles mode.

Hard Difficulty:
----------------
To unlock the hardest difficulty level beat the 3 tournaments of the Star Cup.

Mario Bros. court:
------------------
Win the Special Cup Thunder tournament in doubles mode.

Mecha Bowser Mayhem mini-game:
------------------------------
Win the Mushroom Cup tournaments in singles mode.