The Training Challenges are challenges accessed from the Training tab.  
 
In the Training tab, you will see different theme sets. In every theme set there is a minimum of 5 subthemes with unique prompts and tags you need to dress up your model for. Once you dress up your model according to the challenge tags, you are immediately pitted against an opponent, and graded on a scale from 1 to 5 stars based on how well your clothing tags match the challenge tags.  
 
Winning all the subtheme duels allows you to create a freestyle look for that theme where challenge and clothing tags don’t matter – simply create your most creative look, and your look will be judged by other players. If your rating is sufficiently high, you will complete the theme, earn a trophy, and move on to the next theme. 
 
New themes will unlock as you earn trophies! 
Winning challenges gives you much better rewards than losing, including unique clothing rewards, and winning allows you to progress through Training Challenges.  
 
There is a set of clothing rewards you can get from a certain subtheme, and every time you win a challenge, you have a chance to earn a piece of clothing! The better your score, the better your chance of earning a clothing reward is, and the better the piece of clothing is going to be.  

Make sure to replay the challenges to collect all of the clothing rewards and earn Star Coins that you can use to open Fashion Card packs starting from level 6, that contain exclusive collection clothing.