In the Sega Genesis game Jennifer Capriati Tennis aka Grand Slam Tennis there is a Japanese Debug Menu in the game. I have translated 80% of the menu and uploaded the ROM. In the emulator Fusion, you need to go to "Options-> Set Config...-> Genesis-> AutoFix Checksums" for the game to boot.
To access the debug menu:
1. Enter in all Question Marks (?) in the password screen.
2. Start a match and pause the game
3. While paused, hold down the B button and press Start