Actually, I just realize it's the opposite situation.
Poison was a transvestive in Japan, but was labeled as female in international localizations, but then it sort of got hazy as time went on with no concrete answer but at the same time supporting the former side.
Speaking of transvestite, one pet peeve I do have is that some people don't understand the technicalities of transvestites, and simply label any androgynous male as a transvestite. To be a transvestite, basically the person is psychologically not their associated gender, meaning for example despite being male they identify themselves as female or vise versa. For example, Amane and Bridget are technically not transvestites because they still identify themselves as male, while Birdo and Poison are transvestites because they were male but want to be identified as female.