I have been mentally planning Zelda fairy cosplays for a while now, so I felt the need to put in my two cents.
When it comes to original designs, I believe outfits should be coherent. The top is very pretty, and would look fine with the leggings, but not the tutu. The tutu and the leggings go together, but don't work with the top. I would ask your friend what appeals to her, and find pieces that go well together.
On a side note, plus sizes look AMAZING in corsets. You could look for a Renaissance type bodice and chemise
instead of a lingerie style corset instead.
The tutu itself is a little too "rave-y" for my taste. A longer style fairy skirt
might look more LoZ appropriate.
Here's a great fairy wing tutorial
you might find useful.
Hope this gives you some more ideas for you and your friend. I wish you the best of luck!