Sora's hair colour does change slightly dependent on the game, as does Kairi's, but aesthetically, brighter is usually better.
Now for the new doll...
Cute. I like the hair a lot. The only thing I can say about that is that maybe your should add more free strands?
The batman symbol as the top of the dress works well. The issue with the dress however is the shading at the bottom. I don't like pixelling this type of asymmetrical dress because the shading never seems right to me and it's difficult to explain how to fix (maybe I'll attempt and edit an image into this post later).
I'm with you with scrapping the belt, but I do like the idea of having one. Maybe a more "chain-like" belt, or even just a slightly thinner one would work better. Play around with the proportions first before completely getting rid of it and you might be able to make it work.
I was confused as to why you had one shoe, then realized you needed help with the shape. Shoes are not my favourite part either (runners I can do fine, but heels... yuck), so I won't be of much help. Just know that shoes are not such a big deal and even if it's not perfect, it won't detract from the rest of the doll. That position of foot is hard, and most of the heel won't be visible (which is the reason why it might look weird). Also, I'm not sure which colour I prefer. The gold is definitely more "Batman" though.
I like the necklace and I really like the braclet. My only issue with the necklace is that its difficult to notice. Outline it in a darker shade.
OVERALL, I am seeing so much improvement in you. Keep it up!