Unfortunately, TNA Impact for the Wii does not have a multiplayer mode.
While there are many wrestling games that offer multiplayer options, TNA Impact was designed as a single-player experience. You can enjoy the game by playing through the career mode, taking part in different match types, and creating your own wrestler.
If you are looking for a wrestling game with multiplayer, some options for the Wii include:
You can check online retailers or gaming websites for more information about these games and other wrestling titles for the Wii.