In order to unlock the benefit of doing Carnival Challenges in “Mario and Sonic at the Rio 2016 Olympic Games” is to clear at least 15-20 tournaments.
Tip #1: You don’t have to get the gold medal to achieve this. You need to get either gold, silver, or bronze to clear it. Once you achieve this, you should unlock Carnival Challenges.
Tip #2: In the game, sources say that you can only trigger Carnival Challenges within tournament mode. So far, I’ve noticed that they can be triggered from single matches, Heroes Showdown, and Ghost Matches.
Trick #1: I recommend you participate in Carnival Challenges. The reason is very simple. When you beat a Carnival Challenge you get an exclusive item for your Mii to wear.
Possibility of a Trick #1: I bet that there’s a chance that you might be able to earn music or more features in the game.