What Miis can defeat the mummy ghost in Streetpass Quest/Find Mii 2?

I am currently on Find Mii 2. There is a part where there are 2 enemies: an armored ghost and a mummy ghost. There is one problem: any person I streetpass gets caught off guard and flees!

Is there a specific type of Mii that I need to use to defeat this mummy ghost to get it out of the way?

There is no way to predict if they will scare your Street Pass Miis. Generally if the Mii is level 5 or higher they will not be as likely to be scared off by mummies (unless it is the Marauding Mummy, who tends to scare all Miis).

The best way to get past them is to make sure you have more than one person in your team - they will only scare the first person they encounter (one per mummy), so then you will have people to attack them still.