My daughter has tried many foundations, but they all look very greasy to me. She's trying to hide her bad skin, but I wish I could find the perfect one for her.

If you're willing to invest some money, head to Sephora. They have a color matcher that will show your skin tone and show you what you would wear in every foundation, bb cream, and concealer the store sells. From there, you can pick one that would go with your skin type. Make sure you get a setting powder to set everything in. Some more tips: Try not to get a dewy foundation finish if you have oily skin. You can invest in a toner that will even out her skin. If she has any unevenness she doesn't like, she can try color correcting.