Hi there
EDIT 2:
So this problem is not relevant anymore since I have downloaded the newest essentials pack (v17.2) and the editor does not exist anymore since it's programmed into the essentials itself now. so yea.
EDIT:
I've installed the new V16 of essentials, and the problem is somehow solved (I set everything I had to the new game... it was a big hassle yes), I don't know yet what the real problem is but as a suggestion by @The Omega Mudkip it could be in that it happens because there is a Pokémon specified somewhere that doesn't exist in the 'pokemon.txt' file in the pbs folder. SO if you have that problem make sure to check your pbs files or game if there is a Pokémon entered not specified in the 'pokemon.txt'
I have a huge problem with my Pokémon Essentials Editor as I go to Reposition sprites.
The video shows what I mean, if you have a solution please tell me, I can't seem to find any solution ;-; and it's getting annoying .-.
Thanks!!