Rookie

Rookie is Bowser's amnesiac alter ego and Popple's accomplice in Mario & Luigi: Superstar Saga.

Rookie differs from his normal form physically in that he wears a dark blue mask over his upper head and has green eyes (whereas Bowser's are red in Mario & Luigi: Superstar Saga). Rookie's personality is also different than that of Bowser; Rookie is extremely submissive and loyal to Popple.

When Bowser takes Mario and Luigi to the Beanbean Kingdom in his Koopa Cruiser, Cackletta and Fawful attack the Cruser, causing it to crash in Stardust Fields. Bowser is loaded into Tolstar's cannon and fired to Hoohoo Mountain, where Popple finds him and nurses him back to health.

Mario and Luigi first encounter Rookie in Chateau de Chucklehuck, shortly after seeing Popple for the first time. Popple orders Rookie to fight the Mario Bros. so that he can obtain the Chuckola Reserve. Rookie attacks with hammers and fire breath. He protects Popple very zealously, attacking far more if the Bros. attack Popple.

After the battle, Popple reprimands Rookie for being unable to destroy the brothers, and the two run off in hopes of getting to the Chuckola Reserve before the Mario Brothers. They reach the Reserve, but are captured by the Chuckolator. Mario and Luigi arrive and battle the Chuckolator, but not after the Chuckolator hits the barrels Rookie and Popple are inside, resulting in them flying away.

The Bros. encounter Rookie once more at Woohoo Hooniversity right after Popple finds the Beanstar. Popple orders Rookie to fight the Bros. to protect the Beanstar. This time, Popple and Rookie have even more attacks, but the Bros. still defeat them. After the battle, the angry Beanstar causes Rookie to fall a great distance and remember his true identity. Bowser no longer fights as Rookie in Popple's next fight with the Bros.