Gracie just appeared in my town, and gave me the basic theme.
what are the requirements to pass her check?
A full outfit, including accessories etc
or just a few items?
Here's a guide for you. Look for stuff listed under basic. Do NOT put anything rock'n'roll or flashy with it, you WILL fail, even if it's just one piece. Generally, you need at least two pieces to pass, but Gracie judges hats, accessories, tops, bottoms, socks, and shoes. You can try combining other themes with basic, as long as they don't clash, but it's risky -- if you want to pass with flying colors, I recommend sticking to just basic clothes from the list.
EDIT: Oh, and I forgot to mention -- don't try to combine more than two themes together, Gracie will fail you for that. >.<;;;
Yes, what Panda says is true. You need two items to pass and nothing that clashes with that style. You do need to wear a top and bottom (or a dress), an accessory/hat, and shoes. 4 in all, I think. I once tried to pass without shoes and she didn't go for it.