Brickbuild101
Smash Lord
In the Wii Fit series, the Body Test is a recurring mode in which you a measured to check your COB (Center of Balance) and BMI (Body Mass Index). It's essentially the part where they tell you if your fat or not.
The Body Test is an important and iconic part of the Wii Fit software, so it only makes sense to incoporate it into Wii Fit Trainer's representation in Smash. The way I see it working is that, upon activating it, one of the fighters suddenly has a Wii Balance Board under their feet, and starts the measuring process.
"Measuring...Measuring...Measuring...All done!"
A BMI chart is then displayed with the sections labeled "Underweight", "Healthy Weight", "At Risk of Overweight", and (but only if you dare reach it), "Obese". The chart tells the opponent their BMI, followed by an as-humble-as-possible comment from the Balance Board, and some health advice from him-her/it.
...Go crazy with this one.