DeNA has announced a new Ex Challenge has been added to the the training area as of December 15th, 2019. Marshal is crazy tough and you'll have to use everything you've got to beat him!

Ex Challenge - Marshal

Marshal now appearing in the training area! Take on super difficult bosses! Marshal has been added to the training area as of 12/15/2019 at 10:00 p.m.! Opponents in the training area are crazy tough! Use everything you’ve got to win!

Newly Added to Training Area

• EX Challenge: Marshal

Date/Time Added

12/15/2019 at 10:00 p.m.

Available Rewards

• 1★ Psychic Bracelet ×1
• 2★ Psychic Bracelet ×1

Important

• To explore the newly added area, you must have completed co-op: Challenge Cheren & Hilbert & Hilda (Hard).

Source: https://pokemonmasters-game.com/en-US/announcements/Story_1110_2W_1