A giant Wiggler appears as the boss of Dimble Woods. Bowser first meets him after he pulls up the Giga-Carrot, which was blocking the Wiggler's burrow. This infuriates the Wiggler, who demands that Bowser eat the carrot. As soon as Bowser finishes the carrot, the Wiggler yells at Bowser for destroying generations of hard work and care by eating the carrot (despite the fact that he told Bowser to do so in the first place). He then attacks the Koopa King.
In battle, Wiggler is able to use an array of different moves this time. The most noticeable attack is seen when Wiggler stands up straight and his front pair of feet morph into hands. He then gets a watering can and waters the ground, making a giant Turnip grow there. Two Leaf Guys then pull up the Turnip and hover above the battle on the top screen, waiting to drop it on Bowser as an attack; Bowser is able to inhale the Leaf Guys and the Turnip will drop.
Wiggler's other attacks include ramming and a body slam, where he rises up and attempts to fall on Bowser. Bowser can block this attack by punching the Wiggler's segments, causing him to back up and lower to the point where Bowser is eventually able to punch his head. If Bowser lets the Wiggler fall, he can defend with his shell and Wiggler will rebound. Like the Wiggler in Mario & Luigi: Superstar Saga, the Wiggler is mad and red by default; Bowser must attack all of his segments before he will be vulnerable to attacks.
Later in the game, the Wiggler appears to block the Bros. route. He tells them that after all that has happened to the wood, he is not letting anyone pass without authorisation. When he notices that the Bros. are collecting Attack Pieces, he tells them to 'take responsibility' and collect six. Once they manage to do this, he lets them pass.