The chat is a feature that will allow you to interact with your team members as well as your opponents in Classic games. Remember to be kind!
If you are part of a team, you will be able to communicate with your fellow team members via chat. To join a team, you will need to access the section located in the fifth icon of the bottom bar of the game.
Once you are part of a team, you will be able to see its team members in order from highest to lowest in relation to their respective levels and their connection status. You will find the chat in the third tab of the top bar of the Teams menu.
On the other hand, you will also be able to chat with your Classic mode opponents from the Games section, located on the bottom options bar, in the icon of a list.
For more information on teams, we invite you to visit the article What are the teams?