Single Sculls (or Rowing) is a real-life Olympic event in Mario & Sonic at the Olympic Games and the only one in the "Rowing" category. The point of this event is to cross the finish line before the rest of the players. It involves pressing buttons together to speed up whilst doing the row action.
All that has to be done is for the player to row with excellent timing as fast as possible. It is a race to the finish line and the first one there wins the prize.
To play, only the Wii Remote is needed. Press the button(s) specified on the screen and pull the Wii Remote back. If green notes come off of the character, it was bad and if red ones come off, it was good. For example, if the B Button appears on the screen, the player must press the B Button and pull back the Wii Remote like they're rowing. At the beginning mostly As and Bs appear for the player to press but as the finish line gets closer A+Bs start appearing. When the finish line is incredibly close, the buttons disappear and all the player has to do is pull back the remote with good timing. Only four players can participate in this event and the first of those four across the finish line wins.
 Wii Version
The second mission in the Wii version of Mario & Sonic at the Olympic Games is Vector's. To win it he must simply win the race, cross the finish line first, before his opponent does. His opponent during this event is Bowser.
Shadow's fourth mission in the Wii version is single sculls. To win this mission, Shadow must also beat his rival to the finish line. The only difference between this mission and Vector's is that in this mission the rival is, ironically, Vector and in Vector's mission, it is Bowser.
 Dr. Eggman
In the Wii version, Dr. Eggman's second mission is Single Sculls. He must finish the race but the only difference is that he cannot finish the race in first, if he does he loses. Dr. Eggman must finish the race in the totally awesome position of second! He can do this by being very fast at the start and slowing down at the end.
This would be Princess Peach's third mission in the Wii version. It is single sculls and she must win a race but the difference between this and the real event is that here, she must win the race with at least three perfect strokes. This should be pretty easy for her.
Constant skill, as well as raw power, is required to make the continual adjustments necessary to keep your skiff moving in a straight line. Work your way along the course and cross the finishing line before your opponents to win.