Spray the crock of a 6-quart slow cooker with nonstick cooking spray. Add the undiluted soup, undrained tomates, cream cheese, Velveeta, garlic powder, and onion powder and mix well. Add the chicken breasts and cover with the lid. Cook on low for about 4 hours or until the chicken is just cooked through. Cooking much longer than 4 hours may result in tough chicken and scorched sauce, so be cautious.