Min Min is an ARMS fighter characterized by working in a ramen shop. This is why one of its arms is a dragon. The mechanics of the character are based around using her arms with different buttons. One arm will be controlled with the regular attack button, while the other will be controlled with the special attack button. Its mechanics are very different from what is usually seen in Smash, although it does include familiar movements such as a parry and shooting lightning bolts with its dragon head.
Why did you choose Min Min? Because Sakurai received direct information from the ARMS producer, who literally asked her to be the chosen fighter. This surprised Sakurai and the Smash team, as they imagined that the protagonist Spring Man would be the chosen character. Regarding this, the producer replied “everyone is the protagonist!”.