Well, youre using a hardcoded script command for writing entire battle scripts, not one for making a new command call. Look at the dozens of trigger command examples in the plugin.
They don't interact with each other. Each mechanic is as walled off from each other as I could possibly make them, so that no mechanic ever overlaps with another. You can use different mechanics for different Pokemon in the same team, but you can never use different mechanics on the same...
Because most of these sprites are simply imported from the Gen 8 Pack made by someone else years ago, and those were the sprites it used. That pack used the Gen 5 style full-body back sprites for all the Pokemon, which are not meant for the Gen 3-styled display that Essentials uses. They are...
So, you're trying to hardcode this script? Or are you trying to make a command that you can call within a Midbattle Script? Because what you have here is a hardcoded script.
Which, if that's the case, you havent defined any battlers here, particularly the one that is meant to unTera. You also...
Only reason would be either of the other two things i mentioned.
Also, have you read through the comments in this discussion? This isn't related to your problem, but you are aware that this plugin is currently in an incomplete state with loads of issues, right? Because this seems like a lot of...
The plugin scripts not actually being installed? The plugin PBS files not being installed? The game not actually compiling? Pretty much the only reasons.
The plugin just makes the game read any Pokémon sprite as sprite sheets. It doesn't matter if its an official, fanmade, or custom sprite. It's on you to actually make those sprite sheets yourself, though.