Unique looks aka facial structure eyes light pale skin etc Fit and slim- many companies have their idols stay slim and skinny for the girls and some of the boys are required to. No I let the company choose. So here are some requirements for kpop girl groups who are loved by female fans.
Besides the regular fangirls and fanboys you also have a group of fans known as sasaeng fans or private fans.
I dont mean to deter you from your dreams but the chance of becoming a trainee let alone an idol is extremely small. You can audition as early as 12 years old. You shouldnt become a kpop idol but you still got somewhat small chance in the industry based on your current traits and emotionalphysical state. Fans know that on the surface a combination of good visuals bright personality willingness to work hard willingness to obey agencys requests moderate singing and dancing skills and a positive attitude can catch the attention of entertainment agencies.