Murkrow made its debut in the second generation of Pokemon. However, it wouldn't be until the fourth generation where it would gain an evolution in the form of Honchkrow. Evolving Murkrow in mainline Pokemon games required a Dusk Stone, but the method of evolving it in Pokemon GO is a little different and may take some time.
Currently, the Sun Stone is the only evolution stone to exist in Pokemon GO. For Murkrow, whose evolutions made its debut in the fourth generation, players will need an item called the Sinnoh Stone as well as the required number of Candy. Players looking to have a Honchkrow on their team will need to be patient.
How to Catch Murkrow
Murkrow is a Dark/Flying-type, which means it'll have a higher chance of appearing during foggy and windy weather. There are also Timed Events and Field Research where Murkrow will appear as an Encounter. The easier and quicker way of catching Murkrow is by looking for it in the wild or by doing Field Research, but Murkrow does have a chance of appearing as a Raid Pokemon at Gyms.
While Murkrow's Flee Rate isn't too high, it may not be easy to catch with a regular Poke Ball. Try getting a Nice, Great, or Excellent Throw. Alternatively, use a Razz Berry to increase the probability of catching Murkrow. After catching Murkrow, players can check its Appraisal and IVs. A 3-star Murkrow with a high Attack IV may be worth evolving over a 0/1/2-star Murkrow.
Getting Murkrow's Evolution Items
Murkrow will evolve into Honchkrow with 100 Murkrow Candy and 1 Sinnoh Stone. Candy is easy to farm as long as Murkrow appears frequently on the map. The Sinnoh Stone, on the other hand, is entirely reliant on RNG.
Murkrow Candy
Each time a Pokemon is caught, players will receive 3 Candy. If players give the target Pokemon a Pinap Berry and manage to catch it before the Berry effect "wears off," they'll get 6 Candy instead. Players can get more Pinap Berries by completing different Research Tasks (Field, Special) or by spinning PokeStops. Since players will need 100 Murkrow Candy, it's advised to catch any Murkrow that appears on the map.
Another way to get Murkrow Candy is through the Transfer feature. By Transferring a Pokemon to the professor, they'll get one Candy per Pokemon. Be sure to check the Murkrows IVs before transferring them. Also, keep an eye out for in-game events (viewed by tapping the Binoculars icon). On rare occasions, transferring a Pokemon may give 2 Candy for a set amount of time.
The final way to get Murkrow Candy is by setting Murkrow as a Buddy and walking with it. For a Pokemon to walk alongside its trainer, players need to feed it Berries until the Meter is full. Players will need to walk a set amount of km in order to get one Candy.
Sinnoh Stone
The easiest way to get a Sinnoh Stone is to get a Research Breakthrough. This is obtained by collecting seven Research Stamps (one stamp per day), which players can get by completing Field Research Tasks. As part of RNG, however, this method isn't guaranteed and players will have to rely on pure luck.
The other way to get a Sinnoh Stone is to challenge Team GO Rocket Leaders or partaking in PVP Battles. Team GO Rocket Leaders can be challenged once players obtain a Rocket Radar. PVP Battles can be accessed by selecting "Battle" in the menu. Note that each League has a limit of CP. For example, the lowest League has a cap of 1500 CP per Pokemon.
Once these items are obtained, players can finally evolve Murkrow into Honchkrow. If players have leftover Murkrow Candy, they can start saving up again to get a new Charged Move for Honchkrow, or use them to Power Up.
Pokemon GO is available for mobile devices.