00 - Yoshi 01 - Peach 02 - Mario 03 - Bowser 04 - Boo 05 - DK 06 - Baby Mario 07 - Toad 08 - Waluigi 09 - Wario 0A - Luigi 0B - Daisy 0C - Birdo 0D - Shy Guy 0E - D.K. Jr 0F - Paratroopa 10 - (Model Only) A Dark-Skinned Boy With A Ballcap 11 - (Model Only) A Short Young Girl With Long Pigtails 12 - (Model Only) A Buff Athlete With A Funky Hairdo 13 - (Model Only) Generic Female Tennis Player 14 - (Model Only) A Question Mark?!
Note: To save changes to the SRAM (so you don't have to use the codes again), play and complete one game in any mode with the codes enabled. This will save the data to the SRAM and you will not have to put the code in again to use the new characters.
00 - Hard Court 01 - Clay Court 02 - Grass Court 03 - Composition Court 04 - Super Mario Court 05 - Peach Court 06 - Wario Court 07 - Yoshi Court 08 - Waluigi Court 09 - Bowser Court (NOT The Item One) 0A - Mario Bros. Court 0B - Yoshi & Baby Mario Court 0C - Wario & Waluigi Court 0D - Donkey Kong Court 0E - Mario & Luigi Court 0F - Yoshi & Birdo Court 10 - Bowser Court (Item One) 11 - Hard Court (Beach-?) 12 - Pirhana Plant Court
Select "Composition Court" and begin playing. But what's that? You're only in a black hole and no one seems to be scared that the court and the world is in a black hole and about to disappear!
With this code, you'll win the Piranha Chanllenge easily, but if you're going to play on another game, such as the Tournement Mode, when you swing, you'll miss. Nobody will win anywhere.
Go to anything (Exhibition, Tournament, Etc.). Make sure you have a GS on Mario tennis and put on this code (it may not work for earlier versions before 3.3) Enter the code in and enjoy! When you serve straight, the ball goes by REALLY fast, but when he hits the ball it's sooo weak it doesn't even reach the other side, over the net!