How to Sync Two Nintendo DS Systemsby Carl Baker ; Updated September 22, 2017
The Nintendo DS features multiplayer for both wireless Internet users and local players. Two methods allow DS users to connect to each other locally: multi-card play and DS download, or "syncing."
Instructions for Host
Insert your single-card play enabled DS game into your Nintendo DS and turn the power on. Touch the screen to advance past the health and safety warning, then tap the game icon at the top to start the game.
Press the Start button or tap the screen to advance past the game's menu screen.
Select the option "Multiplayer" from the menu by pressing A on it or tapping it with the DS stylus.
Select the option for hosting a single-card multiplayer game. This will allow other DS users to connect to your DS and play the game with you.
Instructions for Guest
Press the power button on your Nintendo DS to turn it on. Touch the bottom screen to advance to the main menu of the DS.
Tap the "DS Download Play" option on the right-hand side of the main menu. Let the DS scan for any wireless connections in the area.
When a game icon appears on the screen, tap it to join the wireless multiplayer game. Loading times vary depending on what game is being played.