Blue Green Switch

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 labeled as a "Game Level" card. It can only be used in the main game (while World-e does have some levels with turnips growing, the actual card cannot be scanned there, and any attempt to scan it will give the error message "This card can't be used here").

Once the Blue Green Switch is scanned, grass with turnips below appears all throughout the main game, and Mario can pluck them from the ground and throw them at enemies, just like in Super Mario Bros. 2.

English
Make vegetables sprout up in the level, then use them to attack enemies. This card can be used only in the existing game levels. [!]Scan the card once to turn the switch on, and scan it a second time to turn the switch off!

Japanese
オリジナルコースに野菜出現!

Translation
Vegetables appear in the original course!