This guide will tell you how to Add Friends and Play Multiplayer with Friends in Beyblade Brust Rivals.
You will need to open the home screen of your game and then click on the Multiplayer option.
On the multiplayer page, you have to wait for a few seconds and then enter a room code which will be sent to you by your friend. After entering the room code, you have to click on the Battle button to start playing.
