You're going to have to read the labels to get to the bottom of it. If a yogurt's ingredient list includes fructose, sucrose, glucose, or any of the sugars included in this list: www.eatright.org/Public/content.aspx?id=64
, it's got added sugars.
All yogurts have some probiotics in them, as well, some just have more. Again - the nutrition info label on the container is your friend! I'd say, for the most part, stick with a plain yogurt to avoid the sugars, and then add your own ingredients to it: nuts, berries, seeds, etc.