Describe the battle, the trainer, any additional scripts, pokemon, moves and stuff you have added to your essentials version. From what I see, the engine somewhy just don't end the battle when there is no enemy pokemon left.
In any case scenario, you can always ask for help from those who are familiar with Essentials. Ask them to give you a code to force a battle to end and insert it instead of the line with "raise" from code below. It is in PokeBattle_Scene.
if curwindow==-1 raise RuntimeError.new(_INTL("No targets somehow..."))
well, I never really add stuff, just new moves that so far did not touch any double battle and EV/IV screen. I have also deleted the code for z moves and EBS. I also introduced new sprites and songs. I also tried in the older version (v16) and still have this issue. The most changes I did was new mega evolution and specific event encounter using global switch (like specific nature and EV or IV). However, I also tested with non-mega form and have the same issue. I am also using RPGXP
Btw, How do I ask those people that is in Essential? I am new in this and other than RPGXP, this and Essential are the only platform I know. thanks for your patience.
Pokemon Essentials is just the engine implemented onto the RPG Maker XP script platform. You can ask for help on pokecommunity or reliccastle. And I think they would need more information, like battle log, what moves and pokemons have been used etc etc to see full picture.
I would really suggest never deleting stuff, even if you are not going to use it.
okay for those who knows, I have another issue. For some reason I did nothing but I ended the battle with the same pokemon ( I use fearow and carbink and fight mega beedrill in double battle). I got this error.
Message: wrong number of arguments(2 for 1)