A Mortal Kombat 11 beta trailer has been released to go over content that will be in the test, and it has revealed the characters people will be able to use. Baraka, Jade, Kabal, Scorpion, and Skarlet will all be playable during the March 27-31, 2019 beta. As a reminder, only Baraka, Scorpion, and Skarlet were available during the March 15-17, 2019 Online Stress Test.
The Mortal Kombat 11 beta trailer notes that all five of these characters will be available and will have custom character variations during the test. This means you will be able to see and test out these options during the trial when fighting online against other people. It also noted at the 50 second mark that the Klassic Tower will be appearing during the beta and offered a quick look at its layout.
Here is the Mortal Kombat 11 beta trailer. As a reminder, PlayStation 4 and Xbox One owners can only access this trial if they have preordered the game. It begins at 8am PT on March 27, 2019 and ends at 11:59pm PT on March 31, 2019.