This is a save file with the N64 content unlocked. Specifically, it unlocks miniganes and Mario characters to be used in exhibition matches and link-cable battles. The intended method to unlock this content is to connect this game to the N64 version using the N64 transfer pack. Even though this game has been rereleased a time or two on Virtual Console, no effort was made to allow players to unlock this content by any alternative means. It is also quite hard, if not impossible, to find cheat codes to unlock this content. In short, anyone without the necessary hardware is out of luck. Until now.
I made this using Project64 and it wasn't hard, just tedious to get set up. Now you don't have to do it yourself. This file has no used save slots and no mini-game progress yet, perfect for starting a new game. The remaining miniganes are unlocked by beating the single-player game.