Tutorial: Editing Compressed Graphics

[C-Dude]

Are they compressed or in some specific format?

The monster graphics are located from E97000 to ECE3BF, but they're diced and mapped tiles.  Not exactly compressed, but not in a format that is easily or comfortably edited in YY-CHR.

You'll probably want to use FF3SE (A graphics editor designed to handle both the tiles and the pointers)
https://www.ff6hacking.com/wiki/doku.php...util:ff3se

Or you can use Madsiur's branch of that same utility if you intend to expand the monster graphics (though I'm unfamiliar with the differences as I have not used this version)
https://www.ff6hacking.com/wiki/doku.php...l:ff3semod

EDIT: Ninja'd.