Might be an issue with "Plugins\Generation 9 Pack Scripts\[001] Battle\[002] Battle_Battler.rb". I'd recommend re-downloading and checking that all files were correctly downloaded. Additionally, you should download and install the following:
JoiPlay version 1.20.27
RPG Maker plugin version...
I appreciate the screenshots! If it isn't too much of a hassle could we get a gif or a video to see the animation in action with the new graphics? Thanks!
It's not a true fix but you can get rid of the error that appears after saving by commenting out lines 229 - 233 in Plugins\Voltseon's Pause Menu\004_VoltseonMenu_Components.rb".
It's a Ruby issue. You could try a newer version of JoiPlay because I did a quick search and it seems like several UTF 8 issues were fixed in newer versions?
Oh that's an easy fix. The fix for this issue will be a part of patch 7.4. Alternatively, you could try to time the event for the Ruin Maniac to move out of the way, but that's kind of dumb so just wait for Patch 7.4's release.