Idol condition requirements

Generally speaking, a girl who wants to become an idol in Japan, needs a gorgeous appearance, appealing singing voice and outstanding dance ability. But some girls who don’t have any one of these conditions of these really want to be an idol.

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For the verb "want" -- a girl wants/girls want

(In the U.S. I don't think we use the word "idol" the way it's used in Japan. Girls might aspire to become famous, or to be a star. But I left the word "idol" in your writing because I think it's the best word to use when speaking specifically about Japan.)

Keep up the good work!