Preheat oven to 350°.
Place oven bag in a 13- x 9-inch baking dish. Add flour, 1/4 teaspoon garlic powder, 1/4 teaspoon salt, and 1/4 teaspoon pepper to oven bag. Twist end of bag, and shake to combine.
Add corn, beans, and diced tomato to oven bag. Squeeze bag to blend ingredients. Sprinkle pork chops with remaining 1/4 teaspoon garlic powder, 1/4 teaspoon salt, and 1/4 teaspoon pepper; arrange in an even layer over vegetables.
Close oven bag with nylon tie; cut 6 (1/2-inch) slits in top of bag.
Bake at 350° for 30 minutes.