One of the features of the augmented reality game "Pokémon GO" is for players to have additional Pokémon characters through hatching eggs that were captured from PokéStops. These eggs must be walked in different distances of 2km, 5km and 10km, and after completing the required distance, the eggs will hatch random Pokémon creatures.

Last month, the game introduced generation 2 where new Pokémon creatures were added. With this, there are new research studies on the chances of acquiring a particular Pokémon depending on its rarity and distance.

Sliphroad has done a thorough study on the rarity of Pokémon hatched in the eggs with 5,945 samples post-Halloween and with 2,514 samples after the release of generation 2.

The research group categorized Pokémon species into four tiers – common, uncommon, rare, and ultra-rare. According to its findings, each tier is about two times more difficult to hatch, particularly following an almost perfect ratio of 1:2:4:8.

Prior to the launch of generation 2 Pokémon, the chance to hatch a common Pokémon is at 2.56 percent, while for the uncommon, it is about 1.28 percent. On the other hand, rare and ultra-rare creatures have 0.64 percent and 0.32 percent chances to hatch, respectively.

With the addition of new Pokémon in generation 2, there is no very significant decrease in the odds, with common and uncommon Pokémon having the chance to be hatched at 2.54 percent and 1.27 percent, respectively. As for the rare and ultra-rare tiers, the odds are at 0.63 percent and 0.32 percent, respectively.

Given these, the study believes that the rarity of the creatures being hatched in the eggs plays a bigger role than the distance of the eggs being walked.

On the other hand, a Reddit user named Topottsel has also a conducted a study focused on the distance. In the findings, a 5km egg has the lowest odds to acquire a very rare Pokémon at a 0.62 percent chance. Among the three, a 5km egg has the highest chance of being earned at the PokéStops, which may be the reason why players are more likely to get common Pokémon creatures at 4.07 percent chance than the rare and very rare ones.

As for the 2km egg, the chances to get rare and very rare Pokémon characters are at 1.74 percent and 0.87 percent, respectively. The rarest creature that players can hatch in a 2km egg is the ghost-type Pokémon Misdreavus. On the other hand, for the 10km egg, players get 5.13 percent and 2.57 percent chance to hatch rare and very rare creatures, respectively. The two rarest creatures in the 10km egg are Miltank and Skarmory.