The theory I’ve read is about a trick to hatch an egg and get the Pokémon you want (a Pikachu with a 2Km egg, a Porygon with a 5Km egg, etc.). To resume, it says that, for example, if you want to get a Porygon from a 5km egg, you have to incubate it, then go for a walk, and when you got half the required distance (2.5 km in this case), you have to stop and evolve 3 Pokémon of the same type (type normal, such as Porygon).
When you’re done evolving, keep walking until the 5km are completed and you’ll get your Porygon.
I was excited about this, because my boyfriend and I, we are Pokémon Go fans and we both wanted this pokémon! So basically, we went out for a walk to prove if that theory was right, as well.
We put the 5km egg in an incubator and started walking. After we got to 2.5 km, we stopped and evolved 3 normal Pokémon (we evolved two Pidgeys and a Ratatta each one) and then completed the 5km required, as the theory said.
When the time to hatch the egg was come, we were anxious, just to see that a Bellsprout coming from the egg! We didn’t get the cute Porygon, but we both got the same Pokémon, with the same stats. I started thinking if that could be a new theory, that if you and other people put the same km egg and hatch it at the same time (or maybe in certain hours of the day too, for example from 4 to 7 pm), you get the same Pokémon