For me using an IV calculator is too hard. I feel I have an Amoongus I caught with what I am pretty sure is oddly enough a perfect Attack IV of 31(according to a site I've studied for 6 months), it reads "Likes to thrash about." and it never gets covered up by a different one when I have bred it with a power item around 60 times now with several pokemon using the same IV in a chain breed. But occasionally it will say "Somewhat vain." once every 15 times or so, and only this one, no "mischivious" or any other. Does this mean it could have another Special Defense IV at an equal amount? I would think after all the times i bred it if it wasn't perfect it would have shown something else.There are no other kinds appearing but the occasional "Somewhat vain." What happens if they are both perfect IVs is my question, which one shows?
Here is what Bulbapedia says on the matter:
In the event of a tie in highest IVs, the IV that determines the Pokémon's characteristic is decided in the following manner: Start with the Pokémon's personality value mod 6. The result is an index number of a stat in this order: HP, Attack, Defense, Speed, Special Attack, Special Defense. In the event of a tie in IVs, the first IV checked is the IV corresponding to that index number. If that IV is not part of the tie, the game moves on to the next index number in the aforementioned order. If it goes past 5 (Special Defense), it wraps around back to 0 (HP). When the game finds an IV that is part of the tie, that is the IV that will determine the characteristic displayed.
This probably doesn't make much sense to a lot of people. Basically, it chooses one of the stats based on the Pokemon's personality value.