I've inserted about 30 new sprites so far, and then I get to a Drapion sprite, and it breaks.
What I mean by that is, when I look at it in-game, it's not a Drapion. At first, it's a blank sprite. However, I went to another Pokemon (Lucario, in this case) and back to Drapion. The sprite became that of Lucario's with Drapion's palette.
I'm not sure what happened, since all of the other sprites have worked fine thus far.
Fire Red, if it matters.