Keeping in style with previous achievements, patch 8.1 brings a new family challenge: Family Battler
The achievement is made out of 10 sub-achievements, each asking you to complete 15 Battle for Azeroth world quests with pets from a specific family only.
Since there are more than 15 world quests possible, you can pick and choose which ones to finish with each family.
Update with Patch 8.2
Since a recent change, the tamers can be fought repeatedly even if their world quest is not currently up! That means you can go through each tamer and family one after the next without having to stop.
Kudos to Terrace
for spotting it!