From the main menu - select Global Challenge Mode (the code is for this mode).O.K now you should be in the lobby. Next hit the A button which brings you to what I'm going to call the pregame screen. This screen has the game controls shown, random tips (tips which are usually just pop culture references) as well as the words: Press A to start. This pregame screen is where you will do this very simple secret code. Tested & Works for Biology Battle V1.93 (the latest version)

Effect	Code
A woman's voice says: Increasing Conflict Level(instead of her other random sayings). Code increases enemies speed, quantity & spawn rate.	Hold down the Y button at the pregame screen & press the A button (while still holding the Y button down). Thats it! Congratulations!