The Koopa Bros. entered the Bowser tank to fight Mario and try to make him think he was Bowser, with Red imitating Bowser, until the tank was defeated and fell in pieces over the edge. The Koopa Bros. did not fall, however, and continued the fight against Mario, until they were defeated and knocked into the prison cell.
The Bowser tank has 10 HP, 1 ATK and 1 DEF. Mario should hammer or use items, while having Kooper or (preferably) Bombette as a partner. If Mario finishes this phase of the battle, his partner attacks at the start of the Koopa Bros. battle. If his partner defeats the tank, then the Koopa Bros. attack first. (This is assuming Mario and his partner don't switch places; whoever's turn it was going to be next, gets their turn at the beginning of the Koopa Bros. battle).
- The shell of the tank has a picture of Princess Peach inside it