The practice rom ("kz") includes save states, frame advance, cheat codes, warps, memory watches, and other tools. This allows for efficient practice and testing on console, without worrying about common emulator issues like inaccurate pausing and slow pictobox pictures. Be sure to read the manual linked on the download page, and note that references to pressing L are for N64 controllers and translate to c-down on a Gamecube controller.
This table shows useful memory watches for kz. From the menu, go to "watches" to add these and keep track of position, speed, and more.