Mario Tennis: Power Tour - Bowser Star Character

DK Star Character:
Defeat DK in Peach tournament.

Luigi Star Character:
Defeat Luigi in Peach tournament.

Mario Star Character:
Defeat Mario in Peach tournament.

Max Level:
Beat all the characters with one character in Exhibition on level 4.

Peach Dome Court:
Defeat the Peach tournament in either singles or doubles.

Peach Star Character:
Defeat Peach in Peach tournament.

Secret Airport:
To get to the secret airport, beat the Island Open in Doubles or Singles. Note that if you haven't beat it in either doubles or singles, you can't get into the airport.

Technical Difficulty:
To unlock the Technical Difficulty in the game, beat the entire game, including the Peach Dome Tornament, once in either Easy or Normal Difficulty.

Unlock Doubles Characters:
Defeat any of the following in doubles mode to be able to play as them in exhibition mode.

Effect - Code
Chad - Defeat him and Mason on the junior courts
Chas - Defeat him and Mel in the Island Open
Dweezil - Defeat him and Mynx in the Island Open
Flit - Defeat him and Emi on the center court
Jet - Defeat him and Gary on the senior courts
Kyle - Defeat him and Chris on the junior courts
Linda - Defeat her and Shawn on the senior courts
Meg - Defeat her and Sophia on the junior courts
Mel - Defeat her and Chas in the Island Open
Micki - Defeat her and Kyoko on the senior courts
Mynx - Defeat her and Dweezil in the Island Open
Shawn - Defeat him and Linda on the senior courts
Sheri - Defeat her and Willy in the Island Open
Silvia - Defeat her and Sasha on the junior courts
Skipper - Defeat him and Roy on the center court

Unlock mini-games section:
Raise Clay aka Max or Ace's aka Tina's level to 2.

Unlock Singles Characters:
Defeat any of the following in singles mode to be able to play as them in exhibition mode.

Effect - Code
Barb - Defeat her in the Island Open
Chris - Defeat him on the junior courts
Elroy - Defeat him on the center court
Emi - Defeat her on the senior courts
Gary - Defeat him on the senior courts
Kyoko - Defeat her on the senior courts
Mason - Defeat him on the junior courts
Paula - Defeat her on the center court
Roy - Defeat him on the senior courts
Sasha - Defeat her on the junior courts
Sass - Defeat him in the Island Open
Sophia - Defeat her on the junior courts
Tori - Defeat her on the center court
Whisker - Defeat him on the center court
Willy - Defeat him in the Island Open

Unlocking New Power Shots:
To unlock a new Power Shot, you must beat levels one and three on the Power Shot training machines. You do not get a Power Shot for beating levels two or four.

Waluigi Star Character:
Defeat Waluigi in Peach tournament.