Robo Koopa / Captain Lou is Missing

Mario and Co arrive in Robo Land, only to be attacked by Koopa, who's donned a robo suit. They meet up with Bunsen, a robot Mushroom, who temporarily gets rid of Koopa. Bunsen then takes the group to Dr. Nerdnick, the man who was tricked into building the robo suit, and is being held captive by Koopa's guards. Everything goes well, until Koopa returns and captures Princess and Toad.