The World of Warcraft: Shadowlands pre-patch has brought massive changes to Azeroth including a level squish, class changes, and timewalking expansions for new alts. In addition, the update also loosened many of the older Battle for Azeroth requirements needed to unlock the various allied races.
At the end of Legion, the allied race system was introduced to add various playable races without having to wait for new expansions. But first players needed a specific achievement and exalted reputation with a particular faction, meaning they were stuck behind weeks or months of grinding before they got the questline for one race. However, the reputation requirement has now been removed, which makes it much easier to unlock every allied race ahead of Shadowlands.
Void Elves and Lightforged Draenei
The first 2 Alliance allied races are locked behind the You Are Now Prepared! achievement, which requires completing all the major Argus storylines. Afterward, World of Warcraft players must venture with Alleria Windrunner into Quel'Thalas to find a group of renegade Blood Elves and ultimately save them from the Void's corrupting power. To unlock the other race, heroes must help a normal Draenei overcome various trials and his inner demons during the Lightforged Draenei questline.
Nightborne
Fittingly, the Nightborne must first be saved through the Insurrection achievement. Note that this is the longest Legion requirement since it requires doing most of the Suramar storyline first. Horde players can then embark on a trip to Silvermoon where the Nightborne pledge their allegiance after helping fight off some Void monsters and finding common ground with the Blood Elves.
Highmountain Tauren
The Highmountain Tauren can be recruited after finishing Highmountain's main storyline and earning the Ain't No Mountain High Enough achievement. Players are then invited to attend a feast in Thunder Bluff that comes under attack by the Old Gods' forces. Ultimately, the questline returns to Highmountain, where heroes put down the threat and save Spiritwalker Ebonhorn from being corrupted.
Dark Iron Dwarves and Mag'har Orcs
Players first need to earn the Ready for War achievement by setting up 3 bases on the opposite faction's continent and doing the original War Campaign. Fully inducting the Dark Iron Dwarves into the Alliance then requires doing several solo scenarios and even completing The MOTHERLODE!! dungeon. To unlock the Orcs, Horde characters must get the Bronze Dragonflight's help to open a path to alternate Draenor and save the Mag'har Orcs from being annihilated by the Lightbound.
Zandalari Trolls and Kul Tirans
Each of these long-awaited races requires the Zandalar Forever! or A United Nation achievements from completing all of the zone storylines on Zandalar and Kul Tiras, as well as the Tides of Vengeance achievement awarded after finishing the Patch 8.1 War Campaign. Alliance players then embark on a questline to build a new Kul Tiran flagship and renew their pledge to the faction. Alternatively, Princess Talanji undergoes the rituals and coronation to become Queen of the Zandalari, a process witnessed and aided by the Horde through more quests.
Mechagnomes
These mechanized cousins to the gnomes are only recruitable after earning The Mechagonian Threat achievement by finishing the entire Patch 8.2 storyline. Be aware that the final part of this achievement requires entering the Operation: Mechagon dungeon. In the questline, players must save High Tinker Mekkatorque from his near-death state after the Battle of Dazar'alor and ultimately bring all gnomes and mechagnomes together once again.
Vulpera
As the last Horde allied race added in 8.3, the Vulpera questline becomes available after finishing Vol'dun's story and earning the Secrets in the Sands achievement. Initially turned away by Baine Bloodhoof because of the Horde's current state after the War Campaign, the Vulpera decide to help out recovery efforts. Naturally, players end up aiding the Vulpera's solutions which show they do belong with the Horde.
World of Warcraft is available on PC.
Source: Wowhead