The Gauntlet

The Gauntlet is an area in the Challenge Node that Mario and Luigi can access in Mario & Luigi: Bowser's Inside Story. The Gauntlet is where the plumbers face X bosses, harder versions of bosses they have battled before. The X bosses that can be fought in the Gauntlet are:

*Player must beat all previous classes in order to unlock.
 * Class 1
 * Durmite X
 * Straw X
 * Biffidus X
 * Class 2
 * Kretin X
 * Class 3
 * Wisdurm X
 * Magic Rod X
 * Class 4
 * Bowser Memory MLX
 * Class 5
 * Junker X
 * Junker Can X
 * Class 6
 * Dark Star X
 * Dark Satellmite X
 * Class 7*
 * All of the previous classes plus Bowser X

Trivia

 * If the Bros. refuse to go into the Gauntlet, the Emoglobin at the door will mock the plumbers for being cowardly.
 * After beating the Dark Star in the Airway, the Emoglobin at the door will insist they train there for experience, even after Bowser is in the final area, barring the Bros. from returning to the Airway.
 * Scutlet, Chakron and the Dark Star Core are the only bosses that Mario and Luigi don't fight in the Gauntlet.
 * If the Bros. lose against Durmite X before receiving the Badges from Princess Lipid, the Emoglobin at the door will still mention their existence.