In the Sprite Options, Import OW (Sp.Res) and Import Pokemon (Sp.Res) are meant to import pokemon and ow sprites
from the spriters resource sheets.
Specifically:
- Import Ow (Sp.Res) needs as input a file like that
which is 96x128
- Import Pokemon (Sp.Res) needs as input a file like this
which is 64x128
Now, if you want to simply inert the frames for an OW you'll have to do it with th Import Sprite Frames Button. Bear in mind that you cant import one frame with this button. Your image will need to have all of the frames specified in the toy. (Yes, if your OW has only one frame then it will import your image)
The reason you got this warning message is because you tried to insert your sprite's frames with 'Import OW (Sp.Res)'. But, because your image was 16x16 and not 96x128 the toy gives you that warning.
Solution: Import you image with 'Import Sprite Frames'
hope it helps :)