If anyone is interested, recently a interview with Ikeda, made a few months ago (more exactly in November 2012), has been found:
http://www.nanoda.com/gp-publishing-...akihisa-ikeda/
It's in Italian, but with the help of Google Translate, you can roughly learn, what they are talking about.
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Alhazad
I agree that the most likely option of defeating Gyokuro is by using the fact that she uses the Rosario to "fuse" with Alucard.
After all, I think it's pretty unlikely that anyone from the group of good guys is strong enough to defeat Alucard (especially Tsukune, even if he transforms, into his berserk mode), and whenever I hear someone saying something like that ... I have to really control myself, to not say something to them...