Just to add to
@LW001's reply, I've seen some Pokemon-centric animation channels get tagged by YouTube's automated review as for kids. My two cents on it is that with visuals/subject matter that appeals to the below-13 crowd, you need to go out of your way to show that the content is NOT for kids because YouTube considers mixed audience as a type of kids content. Basically, if the answer to the question "would a child click on my video and stay to watch it?" is a yes, then there's a strong probability that it would be considered at least mixed audience content.