The Sweet Card is anything BUT harmful (unless you're a diabetic!) It has the power to sweeten up anything! If you have a major sweet tooth, you'll LOVE this card. It's appearence is sort of . . .odd. (but hey, a lot of cards look odd.)
Sweet appears in Episode 29. How it was captured is currently unknown, but we do know Sakura recieved the card. When summoned, it will sweeten up whatever! What a cool card!