Select any wrestler to play as except the The Miz. Instead, choose him to be your opponent, but de-select him before confirming his attire. Now change the wrestler you are playing as to be The Miz, which should automatically change your opponent to Mr. Fuji. Select Mr. Fuji (which deselects The Miz), then switch the slot you are playing in from left to right. Now you will be able to choose the managers as playable wrestlers.