We already have great IV guides on this website, and these sorts of questions are supposed to be for specific questions if you can't understand a specific IV breeding concept. Here is the most basic IV knowledge needed to breed for a perfect Pokemon.
The IVs of a Pokemon are calculations that modify its stats. IV values range from 0-31, the higher the number, the greater the stat modifier.
First determine what you want. For example, if you want to breed a mixed attacker dratini that uses all of its stats (HP, Attack, Sp. Attack, Defense, Sp. Defense, Speed), then you want a 31 for all of Dratini's IVs.
To breed for IVs, you must use IV tools. These are EV training items, and the Destiny Knot. The EV training items yield a 100% chance to pass on the holder's IV for the stat that corresponds to the training item's EV booster. Example: The Power Lens passes on Sp. Attack. The Destiny Knot causes the holder to pass on more IVs than normal, infringing on the other parent's IV contribution.
Get a male Pokemon/Ditto that can breed with female Dratini/Dragonair/Dragonite. This Pokemon must have a 31 in all stat IV categories. To determine this, use the IV teller located in a post game area. The location varies depending on what game you play, so ask the question or look it up. The teller will say which stats "cannot be beat" which signifies that a stat has an IV of 31. Sometimes you may want a Pokemon to have a Speed IV of 0. Also there are a select few rare cases in which Attack, Special Attack, Defense, and Sp. Defense are wanted to be as low as possible for competitive Pokemon. Trade for a perfect Ditto. It will make life easier once you have it.
There is no easier way to breed for a perfect Pokemon. It's hard. It's advanced. And breeding an almost perfect Pokemon is a lot easier to do, but not a lot easier to understand. Good luck!
