>>18146502I check on battle institute and the IV checker on serebii. I'll explain the process with that Petlil.
>31/02/30/13/31/31 female petlil, destiny knot>31/xx/31/31/31/31 male cottonee, everstone>One egg in the batch has 4 perfect IVs and they happen to be Outstanding with perfect HP, SP.ATTK, DEF, SPEED>This tells me that the offspring adopted the special attack from the father so that the missing IV has to be either ATTK or DEF>Go to Ainstar City where the Hidden Power checker is, he tells me it is Dragon>Go to Battle Institute in Lumiose City(Automatically raises pokemon level to 50)>Put all the relevant information (stats, nature, etc.) into Serebii IV checker>31/1-3/26,27/31/31/31 are the possible IVs>Destiny Knot passes on 5IVs from the parents so I know that the Attack IV is equal to the mother's>I know the hidden power is dragon thanks to the IV checker, so this offspring's Defense is oddThus how I know it's 31/02/27/31/31/31, because if the IV was 26 it would have been HP Ice.