I really enjoyed playing Wii Fit Trainer in the Japanese version. I think I played her twice?
This is all from first impressions:
*Wii Fit Trainer seems very good and definitely a viable tournament character. She will likely not be played much due to more popular characters, but she is definitely a sleeper choice.
*WFT Aerial game is really strong and her moves are a lot faster in comparison to most of the cast. You can typically do Multiple aerials in 1 full hop.
*WFT is unique in the fact that some of her moves hit in front and behind of her(jab, ftilt, fair, ect..)
*Her Special game is great as well. SS is similar to Samus's Charged B attack, but faster and it heals! Side-B flys at a weird angle, Down-B increases the knockback of all her attacks by a good amount(I saw her Upsmash + Down+B kill Bowser @ 88% in one of the videos). I kept messing up the Down-B until someone told me I could press B when it connects in the center. Up-B seems nerfed from the E3 Wii U build because I saw Lilo escaping w/ the move to the other side of the stage, and it doesn't seem to go as far. Custom moves have yet to be seen.
*Grab game is solid, however, I didn't necessarily see many clear follow-up plays. She has more of a control-based grab game where she can position opponent's in disadvantaged positions and charge her B-attacks or wait and punish landing options w/ her strong aerial game.
*Smash attacks seem to lack range, but seem pretty powerful. I didn't get a real chance to test this.
*I think she might struggle vs Projectile characters, but she has pretty good mobility to get around. Someone compared her to a weaker Captain Falcon, which I don't agree w/ but her aerial game is similar in a way I guess, lol.
Overall, I enjoyed playing WFT and can't wait to use her/him in tournament. I don't think her player-base will be large, but she is worth trying out and playing!