Newly annouced Etemon will be played by Ore no Graffiti, from the Shikagoroshi theatrical company.
In addition, the voices of the digimon will be played by their original anime voice actors. How will they be appearing on the stage play is still unknown. Judging by the poster, many fans speculates that they might appear in 3d hologram.
The offical twitter posted more pic of the casts of Taichi and Yamato: