Boo

Boos are the main ghost enemy in the SMG series.

Attack Strategy
Like in other games, Boos follow behind Mario, hoping to hit him. If Mario looks at a Boo, it will freeze, turn into an object it will drop upon defeated, and not move unless Mario looks away.

Trivia

 * Boos were made by Takashi Tezuka's wife, as she is shy, but bursted into anger upon Tezuka coming home late.