Blue Green Switch
From the Super Mario Wiki
The Blue Green Switch is an e-Reader card for use with Super Mario Advance 4: Super Mario Bros. 3. It was included in the Series 2 set of cards. Although technically a Power-Up card, it was labelled as a "Game Level" card.
Make vegetables sprout up in the level, then use them to attack enemies. This card can be used only in the existing game levels.
Vegetables appear in the original course!