Pokémon GO has a number of rare Pokémon, but a few of them are far more in-demand by players who are either looking to finish off their Pokedexes, or are looking for a rare and powerful Pokémon to take over a gym with. Dragonair, Dragonite, Gyarados, Snorlax and Porygon are, to some degree, the closest we’ll get to legendary Pokémon until the special events start rolling in.
Porygon, oddly enough, tends to hatch from 5km eggs fairly often, although you can also find them in 10km eggs occasionally. Other than that, the best place to find a Porygon is in a crowded urban area. Specifically, if you are somewhere near a casino, Porygons will be found far more frequently. This makes sense considering that’s where Porygon was found in the original games. So if you live near Reno, Vegas, Atlantic City, Biloxi or another casino hub, take a day trip for some Pokémon hunting.
Dragonair can most commonly be found near water sources, as can Dratini, which can evolve into Dragonair when you have 25 Dratini Candy. This can include oceans, lakes and rivers, so if you live near a large body of water, make a road trip to catch Dratini or Dragonair. Eggs are also a common way of earning Dratini and Dragonair. Use the Ingress trick to find a good water spot crowded with Pokémon.
Dragonite, unlike the other two dragons, is most commonly reported in wooded areas or parks, but predictably, it’s a far more rare find than Dragonairs and Dratinis. They can sometimes hatch from 10km eggs, but that’s a very rare find. The most common way to get a Dragonite is to catch Dratini and Dragonair, load up on Dratini Candy, and use the 100 required candy to evolve a Dragonair.
The most common way to get a Snorlax is to hatch one from a 10km egg. Make room for them in your egg stash, and as soon as you get a 10km egg, start moving around. In addition, Snorlax most often shows up in land-based areas, especially around roads and, typically, suburbs. They show up EXTREMELY rarely, though, so generally, the 10km egg is the best bet.
Gyarados is one of the most frustrating, due to the fact that you need 400 Magikarp candy to evolve one into a Gyarados. Wild Gyarados have occasionally appeared near large bodies of water, but they are so exceedingly rare that it’s arguably easier to catch and trasnsfer massive amounts of Magikarp until you get enough candy to finally evolve one into Gyarados.