When playing on any stage, telling the color of a Mii's armor can help you identify their strategy of attack.

Black: Have faster reflexes. Act almost as a boss.
Green: Does not block, only swings sword.
Orange/Gold: Almost always blocks.
Pink/Red: Use an equal amount of blocking and swinging, almost immediately counters attacks made.
Purple: Uses defence more often. They alway change their direction of defence in attempts to trick you.