As you may expect the best Warlords Hunter pets guide is made by WOW Insider. I just want to share this post, because the information is very important for every hunter who will play WOD.
"Warlords of Draenor is introducing five new hunter pet families -- hydras, riverbeasts, stags, clefthooves (exotic), and rylaks (exotic). That brings the grand total to 48 pet families. Many pet abilities have also been changed to fit the buff and debuff changes in Warlords. Exotic pets are more differentiated from standard pets in that they all have a total of three special abilities or buffs instead of just one or two. You'll be able to start taming pets from the new families with patch 6.0.2 (except for riverbeasts and rylaks which only exist in Draenor)."