For the bow, there's a tutorial on how to make the bow on a Sailor Moon collar; just don't use strong interfacing to give it that limp but flowy look.
And for the...dress thing, I think you could use a tunic pattern off this site:
Just be sure to make it longer, and you obviously don't need to include sleeves.
And in the future, please post reference pictures with your requests--it makes it easier and faster for people to help you, because not everyone knows what Zatch Bell looks like. ^^;
"Katsu, every time I see your avatar I automatically think, 'Wow, she's really annoyed today!'"
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