Unlock all games
Press Up, Down, Up, Down, L1, L2, L1, L2 at the game selection screen.
Easy W.W. Score
When your playing Wishi Washi to cheat you have to put your hand over the cam & wave it around. (This gives you a high score)
Wrong dialog
If you beat the robot the trainer will say: "you'll make that robot..." But the on-screen subtitles clearly read: "That'll make that robot..."
Do the games easy
Choose any game right. And then see as soon as it starts go quite close to the camera (but not too close) and just stand there for ages and you are guaranteed a high score.