After looking over the sprite I'm using, I can be absolutely certain of several things:
Firstly, the sprite is currently using 16 colors, and is indexed - While I had to set it to indexed, it was already 16 colors because I extracted it from an Emerald rom hack
All the colors have 0 or 8 as their ending value, as listed in the HTML notation box - This also isn't surprising since, again, I extracted it from an Emerald rom hack, where the color limitation is still in effect.
The only color that seemed off was the 16th color, which was ffffff, to which I ask: What would I change that to; since it worked in Emerald why wouldn't it work here?