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.
That's a typo, it'll be fixed in the next update, thanks!