Cook the macaroni according to the package directions, adding the corn during the last 2 minutes of cooking.
Drain and rinse under cold running water to cool. Drain well and place in a large bowl. Stir in the bell peppers, tomatoes, carrots, zucchini, celery, onion, basil, and green onions.
Whisk together the sour cream, mayonnaise, lemon juice, salt, and pepper. Stir into the salad. *Tip: cover and refrigerate at least 1 hour to allow flavors to blend.