Yes-but the REASON why flavored f-f yogurts are not Core is because most widely used brands contain sugar. I think WW wanted to make it simple and just say plain so we wouldn't have to worry about the labels and what has sugar and what doesn't. They wanted to keep it simple.
ALL dairy products contain a few grams of natural sugars in them anyhow-so checking the grams of sugar/carbohydrate on the label isn't the answer as far as seeing if a brand contains sugar-you have to read the actual ingredients and check for sugar, corn syrup, fructose, fruit juice, etc. It is the ADDED sugar that you are checking for.
If you do want to use flavored yogurt-I say check the labels and go for a sugarless one. WW is just trying to find a way to "pare down" the list and simplify things-but a totally sugar free fat and free yogurt that contains a touch of vanilla and Splenda is the same to me whether you buy it that way or mix it yourself.
You have to think about the point behind the rule...why they made the rules and the food list. It is the sugar/refined carbohydrate avoidance. There are many WW members used to eating fat free yogurt that has sugar in it...and they are trying to get away from that on Core/South Beach/SugarBusters/other no white flour-no sugar diet plans.
As a moderator I have read the books on a lot of these very similar plans and the research behind them-and why you are allowed this and not that. It is about reducing the refined carbs and sugar in our diets...the "trigger foods" that tend to cause overeating. The WW list is very simplified to make it easy for everyone, that's all.
Blue Bunny Light 85 is a brand that is fat free and has no added sugar or juice to sweeten it. It is sweetened with sucralose/Splenda only.
I am saying-that no matter what the list says-that as long as the flavored yogurt contains no added sugar in any form-then I am considering it Core. You can do the same if you want, and if you don't want to-then don't. My stepfather is a former pro-bodybuilder, my mother is a nurse and has worked in the dietary field for EONS...and I was a gestational diabetic (diabetic when pregnant) and had to watch sugar in all forms during my pregnancies. I know what I know.
WW just doesn't want us all avoiding sugar and refined carbs in most other forms thoughout our day, and then be eating them in our Yoplait Light and not realizing it.
JMHO,
Aphil
Milk products question
, one list has that it's okay to eat ff yogurt w/fruit. I'm used to having a Yoplait Light FF Strawberry/Banana yogurt for "dessert" after lunch at work. I know I could eat it and count the points, but was curious if it is or isn't Core? 
I doubt that any cream cheese is core. The jello is instant in a box. There have been discussions, on other boards, about making SF cook 'n serve jello pudding with FF milk and having it be Core. I'd have to look at the Food Companion. Pudding is a take it or leave thing for me, so I don't make it much anyway.
But I'm sure it's one of those "trigger potential" foods that we may overeat....and maybe because it's commonly eaten on bagels! 
