Try using JoiPlay version 1.20.015 and the RPG Maker Plugin for JoiPlay version 1.20.19. These are the versions players have confirmed work with the game.
Check if the plugins folder is intact and make sure it is not missing anything. Alco check your version of JoiPlay. I think the issue might have to do with how JoiPlay supports UTF-8 encoding.
There should be an "encounters.txt" in the game folder. That lists the available Pokemon for your version of the game.
This game only has a battle tower.
unzip just like the main game folder. copy and paste contents of patch into game folder and hit overwrite all.
Yes. Game Corner prize. You...
You don't. v6 only goes that far.
Okay so if the backtrace is correct the issue is likely the loading of the "size" property added by the Essentials Deluxe plugin. When that feature was added to said plugin, it required the start of a new save so I can only assume your save file is old enough...
I'd be fine with it if I get to see something unique and interesting done with the story. However, it might take some getting used to, as sometimes games change a legendary's personality completely and that usually messes with my perception of said legendary for a while.