Trainer

The Trainers are characters in the Wii Fit series who serve as the player's trainer in Yoga and Strength Training activities. The player can choose their preference between the Female Trainer or Male Trainer, though they may occasionally fill in for each other on some sessions. In Wii Fit and Wii Fit Plus, both trainers wear different-colored clothing depending on the type of activity, matching the color of their studio (blue for Yoga, green for Strength Training, and yellow for either when accessed through My Wii Fit Plus). In Wii Fit U, the designs of the Trainers have been updated along with the overall presentation of their activities, having more detailed faces and always wearing green.

Super Smash Bros. series
Starting with Super Smash Bros. for Nintendo 3DS and Wii U, the Trainers appear as a playable fighter under the name Wii Fit Trainer, which has since been used in other crossover appearances. Most of their attacks and other animations reference the activities they instruct in their home series, while two of their Special Moves utilize equipment used by Mii characters in Balance Games and several of their standard moves being yoga poses. Their design is largely based on how they appeared in Wii Fit Plus (with alternate colors representing those seen with Strength Training and My Wii Fit Plus), but their faces were updated in Super Smash Bros. Ultimate to appear more detailed similarly to in Wii Fit U, a change made at the request of the Wii Fit development team.

Super Mario Maker
In Super Mario Maker, the Female Trainer appears as one of many unlockable costumes to use with the Mystery Mushroom. She stands and runs while holding the Dancer pose, and her voice is heard when she jumps. She also appears as part of the Wii Balance Board's costume, standing on him in the Dancer pose for the "taunt" the costume performs when holding up on the + Control Pad.

Trivia

 * The files of Wii Fit contain an unused, unfinished model for a realistically-colored Female Trainer.