When setting up the Battler Icon the lesson said to use the following Stretch Mode:

Change the Stretch Mode to Keep Aspect Covered, so the node always retains the image’s aspect ratio.

I found that this resulted in the image's edges being cut off, and checked the final code example to see that it was using a Stretch Mode of Keep Aspect Centered instead.

Also, I don't think it's mentioned in the lesson, but the UIBattlerIcon root node needs its margins adjusted so that the center of the icon is aligned with the center of the UITurnBar.