Have the Ulti-Free badge (bought in Fawful's shop for 90 Beans) on Luigi and the Shroom Badge A on Mario. Also have lots Super, Ultra, Max Mushrooms; Drops;, and 1-Up Supers. Start by hitting her as hard as you can with repeated Mix/Copy Flowers every turn with Luigi. Just have Mario attack normally. When you take off half her HP (3000 HP), she will appear to die, but instead turn into a much more powerful form with four tentacles and a cluster of tentacles at her feet. When this happens, target her foot, or better yet all of her, with a Mix Flower. When the foot is destroyed, she gets shorter. This allows you to target her crown. Destroy or knock off her crown so that your attacks will work on her. Repeat this process until she is defeated and watch what comes next Be prepared; she has 6,000 HP.