See forum #199422. Cosplay photos aren't disallowed and it was wrong to simply put it in the off-topic section in the upload rules. This change wasn't made by an admin or moderator, but some builder who did it, without any forum discussion. Cosplay photos can still be flagged, but should be because of poor quality and not because of a relevance check. On the other hand, cosplay photos should still be uploaded rarely, of course.

Guaro said:

See forum #199422. Cosplay photos aren't disallowed and it was wrong to simply put it in the off-topic section in the upload rules. This change wasn't made by an admin or moderator, but some builder who did it, without any forum discussion. Cosplay photos can still be flagged, but should be because of poor quality and not because of a relevance check. On the other hand, cosplay photos should still be uploaded rarely, of course.

I don't visit forum that much so i didn't knew this but I will keep this in mind.