Answered Pokémon Black, problems breeding the perfect pokemon

[Grendel8]

Hey so I’m playing Pokémon Black (not black 2) and I’m trying to breed the perfect Dratini (meaning 31ivs in all 6 stats)
 

Now I’ve taken my male and female Dratini to the iv judge in the battlesubway and he says the following for my male:

 

”This Pokémon has Outstanding potential overall, incidentally I would say the best potential lies in its attack stat, defense stat, Sp. Attack & Speed. It can’t be better in that regard.” (So I’m under the impression that indicates perfect stats in Attack, Defense, Sp Attack and speed).

 

Then he says this when judging my female Dratini: 

 

“This Pokémon has relatively superior potential overall. I would say the best potential lies in its Hp, attack, special defense, speed. It can’t be better in that regard.“ (So I assume it indicates perfect stats in Hp, attack, sp defense and speed). 
 

So obviously not guaranteeing anything in way of hatching the perfect Pokémon in every shot but given a chance... The thing I don’t get is how some of these eggs I’m hatching don’t even have two perfect IV’s when both parents have perfect attack and speed... Sometimes the egg doesn’t even have one perfect stat! And I don’t understand what I’m missing because I thought a Pokémon bred has 3 random IV’s from one parent and 3 random IV’s from another? 
 

if anyone is knowledgeable about breeding and has information on what I’m missing here please instruct me. It would be greatly appreciated!!!

[Auke1993]

If I recall correctly, there's a held item you need to hold (Destiny Knot maybe) to make it certain you pass on 3 IVs from a parent.
I used to know it better, but it's been a little while since I last did competitive breeding.

A quick search on Bulbapedia or Serebii on how to pass on IVs when breeding should being up the answer.

[Patrick]

Yep, Destiny Knot held item is what you're looking for.

[misty_lax]

Destiny Knot only works in breeding Generation 6 onwards (X and Y onwards) so I don't think it will work on his game. The only way to pass IVs in Black and White is the Power Items.