In a large bowl, combine rice and ground beef. Using your hands, shape the rice/beef mixture into meatballs, about golf ball size, and place them in a large casserole dish (do not layer balls more than 2 layers deep). Use an additional casserole dish if necessary.
Add the chopped peppers and onions on top of the meatballs.
In another large bowl combine the garlic powder, chili powder, black pepper, stewed and whole tomatoes and stir well.
Pour the mixture over the top of the onions and peppers in the casserole dish.
Cover with lid or foil and cook for 2 hours 30 minutes or until rice is thoroughly cooked.