https://www.polygon.com/2018/5/17/17364350/mario-tennis-aces-demo-nintendo-switch

Mario Tennis Aces, due to launch June 22 on Nintendo Switch, is getting a free demo beginning next week, and a three-day multiplayer tournament at the beginning of June. Switch owners may try out the game from June 1-3 in a pre-launch tournament, Nintendo announced this week.

The demo will be found in the free software group in the Nintendo Switch eShop beginning Thursday, May 24. Users who join the tournament when it begins may choose from four playable characters — Mario, Peach, Yoshi or Bowser — and compete in online multiplayer matches. The winners of those matches will earn points that can be used to unlock as many as five additional characters.