89555459_ners___Pokémon_Essentials_Wiki__What_it_means
[Comment] Backdrop: Mystic [What it means] 
Sets the battle background for this battle. For this example, the background images will have filenames of "battlebgMystic.png", "playerbaseMystic.png" and "enemybaseMystic.png".
Trainers - Pokémon Essentials Wiki
What it means