Blizzard Midbus

Blizzard Midbus is the stronger version of Midbus, appearing in Mario & Luigi: Bowser's Inside Story. When Bowser meets with Midbus in Princess Peach's Castle, Fawful powers him up, changing him into Blizzard Midbus. In this form, Midbus is completely blue, with a brown, furry back, wearing a crown, and is a lot stronger than before.

Mario & Luigi: Bowser's Inside Story
During the battle, Blizzard Midbus can use many ice-related attacks. In one of his attacks, he can jump onto a gigantic snowball and try to roll over Bowser with it. There is a Bob-omb sticking out of it which Bowser must punch to make the snowball explode. After Blizzard Midbus' HP is halved, he sometimes hides the Bob-omb so the player will have to remember where it is.

Blizzard Midbus can also send Snawfuls out of his crown to attack Bowser. They can throw little snowballs at Midbus to make him recover HP. Bowser can inhale them, though, and allow Mario and Luigi to battle the small foes. Blizzard Midbus also attacks by using snowballs. If he looks at the snowball, he won't throw it at Bowser, but if he looks at Bowser before throwing it, it will go towards him. Then, Blizzard Midbus will attempt to punch him. It can be countered, as usual. Once again, he attacks by body slamming Bowser. Bowser's Fire Breath can cause a lot of damage to Blizzard Midbus.

After Blizzard Midbus is defeated, he gets frozen in a gigantic block of ice, leaving only Fawful to contend with. He then begins pumping out an infinite stream of frosty gas from his snout. Bowser needs to use the gas to help the Mario Brothers progress inside his body. It's unknown what happened to Midbus after the events of the game. If followed logically, he may have unfrozen by then, or arrested when the Toads who were rebuilding Peach's Castle.

Trivia

 * Blizzard Midbus has the highest HP of any required boss in the game, exceeding even the final boss.