Well, if you want to know its IV, go into a Wifi LV 100 and copy down the Rhyhorn's stats, and then put them into the IV calculator, where it will have accurate IVs.
It means that the defense IVs could range from 10-31, but since it is LV1, it is very inaccurate. That is why it is recommended to go into Wifi LV100 Battles to check IVs.