I have set up this achievement on an achievement world I am building. Most of the achievements are obtainable but it's still a work in progress which is why I have cornered off this achievement as it definitely works.
Simply use this link https://bit.ly/2Vm9y97
to access a dropbox folder where the world is. The world's name is "Update 1.11.1 Achievements". For iOS, try downloading the .mcworld file first, once it is downloaded you should be able to press "open with Minecraft" and it will automatically open with Minecraft. If that doesn't work, then on a computer download the .zip file, extract it and add it to your worlds via a program like iExplorer.
When the world is downloaded and is successfully added to your worlds, make 5-6 copies of it before you open it (if you don't, you will need to download and add the world again). Now for the achievement. I have it setup so only butchers are spawned in as they seem to be the most efficient villager to use for this achievement. The spawn location is the exact same for the host as well as anyone who will join and is right in front of the achievement area so you don't have to run 500 blocks to get there. Your inventory is already filled with the required meat so all you have to do is go to each villager and trade with them to receive emeralds. Theoretically it should only take 5 saves as you should get 200 emeralds per run, but I recommend downloading that 6th save just in case you need it.Note: For iOS (and Android), make sure to press the "trade" button as the progress tracking is slightly unreliable and it may not count otherwise.