Pocket Plants are NEW Bro Items in Mario & Luigi: Sibling Rivalry.
These work just like Pocket Chomps, the main point is the Piranha Plant inside the capsule to come out and chase the brothers. When the Wario Bros. use this item, the Piranha Plant comes out and starts chasing Waluigi because he's faster and Wario just sits on top of the plant. Waluigi runs and jumps on the enemy with Y. And the Piranha Plant and attacks while chasing Waluigi is running. When the plant attacks, the player must press X because Wario is sitting on it. If you fail, the plant will slow down, but if your timing in pressing X is correct, the plant will speed up and grow more angry.