When playing knockout do the roll. Stay still the eyetoy responds to motion. Note: this cheat works on any game.
Knockout: Easy win
Stand directly behind your opponent and beat them up. When they get ready for a punch, freeze and they will not hit you.
Move penalty machine in Football
After selecting "Football" at the game selection screen, select the penalty machine. When saving penalties, use the D-pad on controller one and move the Left Analog-stick around. This will move the penalty machine. You can now move the machine wide and make it shoot. To make it shoot, press X.
Table Tennis: Easy win
When you are hitting a ball back to your opponent, spin your forearms around very fast and you will not miss it.