I'm curious about something.
With this alt. costume, when the game is localized into other languages, they will have to take on account the gender change because some languages make distinction between male and female trainers.
What I mean is Wii Fit Trainer could refer to both male and female trainer, while on the Spanish or Portuguese websites, they explicitly refer to her as a female trainer ("Entrenadora de Wii Fit" or "Treinadora do Wii Fit") which means they will have to program something to change the name slightly to refer to a male trainer, which would be "Entrenador de Wii Fit" in Spanish or "Treinador do Wii Fit" in Portuguese.
Just a small observation that the localizers need to take on account if the game is to be translated to other languages that have gender distinction (such as the two I mentioned above), because it would be really weird to see the male trainer being referred as a female due to what could be an oversight in localization.