Move relearners will not teach moves added to the level-up learnset of a pokemon via editing the JSON file. useExternalJSONFilesStats has been enabled in pixelmon.hocon, and I have added some moves that are only obtainable by old generation TM /transfer as level 100 moves. A pokemon newly leveled up to 100 learns these moves as expected, and using /movelist (Pixelextras command) displays the moves alongside levelup moves. But if these moves are forgotten a move relearner does not display these moves as an option.
Below is the contents of Lunalas stats file, where toxic and defog have been added as level 100 moves:
https://pastebin.com/ryqmncrC (pastebin'd by SirDoof)