An Epic Buddy

Edit: Apparently it turned out that any originally green (uncommon) quality follower can fulfill the acm criteria if you have some luck and they end up as purple color due to the basic upgrade chance so the list below is irrelevant as well as the achievement itself.

Currently, there are 5 followers in the game who can be recruited in their original epic quality. The achievement has been granted as soon as you obtain any one of them.

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• [follower=225] - granted by completing The Steel Has Been Brought acm in any non-LFR BRF.
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• [follower=177] - granted by completing Come With Me If You Want to Live acm in HC Slag Mines.
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• [follower=178] - granted by completing Leeeeeeeeeeeeeroy...? acm in HC UBRS.
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• [follower=203] - [item=119283] will be available right after you reach rank 5 in Brawler's Guild (wod edition).
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• [follower=455] - reward of For The Children!, offered from the daily random quest pool of [building=34].
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For more detailed instructions on how to get these guys you may check out the Tritox's WoD Follower Guide and/or the comments on the particular achievements / quest pages!

I've got 20 followers and none of them is epic :<. Luck is not with me.

After your followers reach lvl 100 you can rank them up to rare and epic using 'experience'. Although this takes a long time.