Updated November 20th, 2019: It's not been confirmed that Galarian Linoone will evolve into Obstagoon when reaching level 35, but only at night. However, the time of day outside of the Wild Area being set to plot-relevant times until the post-game. The only way to acquire Obstagoon (and other night evolution Pokémon) before reaching the end of the game is to level it up at night in the Wild Area.
Now that Pokémon Sword and Shield has finally launched, players are discovering all the ways the new Pokedex is rolling out in terms of rare and special evolutions. One of the most interesting so far comes from the new variant of the Galarian Zigzagoon and its two evolutions, Linoone and Obstagoon. The final version is both new to the game series and is somewhat rare, or rather, requires special attention to attain.
The first step is to find a Zigzagoon, which is relatively common in the open world. YouTube content creator nirth explains that the Pokémon has a 2% of being found and shows how with some running around in grassy areas in Route 2, players can spot one with a little effort. If one does not appear, players can simply run into all of the Pokémon in an area and then “Run” away from the encounter to reset the spawning of new Pokémon to catch.
After finding a Zigzagoon it will need to be leveled up to about level 20 to evolve into Linoone, or alternatively, caught in the wild once further into the game. Linoone then needs to see a lot of action through combat before it will evolve into Obstagoon.
UPDATE: Now that players have had more time with Sword & Shield, we have a better idea of how to evolve Linoone. According to Bulbapedia, Linoone needs to reach level 35 and then level up at night. Reaching level 36 or beyond in the dark will trigger its evolution into Obstagoon!
Once evolved, its entry text reaffirms that non-stop combat is the best way to trigger an evolution, which reads, “It evolved after experiencing numerous fights. While crossing its arms, it lets out a shout that would make any opponent flinch.”
Here is where the internet seems to have a broad range of opinions on when it will level. Nirth for example states that his evolution came at level 35, whereas other players are reporting that Linoone did not evolve for them until reaching between 50-55. One thing is certain, and that is that players should simply focus of making Linoone fight as often as possible to bring the evolution as soon as possible.
For players who want to collect Obstagoon but have no interest in using it or its previous evolutions, the option to simply catch it also exists. After collecting most of the game’s badges, players will be able to find it in the Bridge Field region and should have one to trade with Team Yell Grunt for a Kanto region Mr. Mime.