The chicken, pepper, onion, and pineapple should all be cut into bite-sized pieces, but still large enough to thread onto skewers.
Place the chicken in a shallow bowl or pan. Combine the orange juice, soy sauce, oil, and garlic cloves and pour over the chicken. Make sure the chicken in completely coated. Place the chicken in the refrigerator and marinate for at least an hour or more.
Pre-heat grill to medium.
Place peppers and onions in a small bowl and drizzle lightly with olive oil.
If using bamboo skewers, they need to soak in water for 30 minutes before using. Thread the chicken, peppers, onions, and pineapple onto skewers. Don't thread too tightly, leave some space between pieces so the food can cook evenly and properly.
Place chicken skewers on grill and close lid. Cook for 5 minutes. Turn the skewers and grill for another 3-4 minutes or until chicken is cooked through.