This game has unused text.
Mario's Tennis is a VIRTUAL tennis game for a VIRTUAL system! \o/
Present in the game is a list of the in-game characters: Mario, Luigi, Princess (Peach), Koopa, Donkey (Kong Jr.), Toad, and Yoshi. Amongst these at offset 7D6D3 is "Cassarin", the Japanese name of Birdo (a more literal translation is キャサリン, Kyasarin, but the intended name is "Catherine"), who is otherwise not in the game.