You really should double check the WW materials to be sure since the lists are often long and vary from brand to brand. Quaker old fashioned and quick oats are Core. There are some rules about instant so you should look them up. I don't eat instant, so I can't advise.
The same is true for yogurt. I'm pretty sure the answer is that only FF PLAIN yogurt is Core. We do have a granola recipe on our site. I'm pretty sure that Sandra created it. I think it was an all Core recipe but it might be a Core plus one.