There’s a lot of Stubborn Mii slander here, which is understandable, but let’s add some balance:
Kind characters will be unable to take an action every other turn if a quarrel is happening because they’re too busy being worried about it.
Energetic characters have a faster walking and running speed than the others and if they manage to go fully offscreen during a walking section the rest of the party gains resentment.
Cool characters insist on going the more dangerous path and this will be final if the main character is not present.
Airheaded characters get distracted by winning and forget to follow the party afterwards, getting lost.
Laid-Back characters will sometimes just… spend money without you knowing.
Cautious characters will not get any sleep some nights, being too busy checking for hidden traps in the inn.