You can fight against someone else using one DSi. One player gets to hold to left side of the DS which makes the L button used for attacking and the second player gets to using A, B, X, Y, and R. Player Two's controls are just like Player One's except mirrored. Your goal is to knock the other player out by attacking them. If your HP is to go low enough, you can use a desperation move by tapping the touch screen on your side. A desperation move is a powerful attack that can severe damage your opponents if used correctly. You can have both players choose the same character.