For dressing, in a 1-quart screw-top jar, combine the oil, vinegar, garlic, salt, and pepper. Cover and chill up to 1 week. Shake before using.
Up to 6 hours before serving, arrange tomato wedges on two to four large platters with rims. Top wedges with the baby tomatoes and mozzarella. Cover and chill. Just before serving, sprinkle platters with the shredded basil and drizzle with dressing. Top with whole basil leaves. Makes 50 servings.