Here's a list of Vendors that require "unlocking" plus specific vendor pets that also require extra steps before you can purchase them.
Nigel Rifthold (vendor sells 5 pets)
Note: You do not have to do the quest chain to "save" Nigel before completing the process below.
- Head to Anyport (western coast of Drustvar)
- Buy 10 Tirasreli Gourmet Chocolate from Xun Xun Sweetflower
- Travel to 52,31 in Drustvar (west of Fallhaven, just above the "F" in the name)
- Climb up a hill and enter a tree house
- Loot the chest that's inside if you haven't already
- Click on the chest a second time (consumes the chocolates), Nigel will appear and be a vendor.
- Horde - Complete Killing Cannibals, Just Say No to Cannibalism and Shoak's on the Menu to get this NPC to appear in Gloom Hollow, Nazmir.
- Alliance - Head to 55,36 and find Kajosh. Complete the quest chain. Shoak will appear in the Horde camp, Gloom Hallow (Alliance can interact with him, but you'll agro the camp).
Alternatively, Blind Wunja sells the same pets as Shoak and Alliance can interact with her without agro'ing any Horde.
- Complete the quest chain that starts with A Lost Flute
Unlocking Specific Vendor Pets:
Ranishu Runt - sold by Jenoh (H) Accursed Hexxer - sold by Shoak (H) OR Blind Wunja (A & H)
- Complete An Ancient Curse
- Complete the Torga's Eternal Return storyline, which then opens the quest chain that begins with To Gloom Hollow
- Complete Lil' Tika
- Complete Cala Cruzpot's quest chain
- Earn Get Hek'd achievement
- Complete the quest chain that starts with An Explosive Opportunity
- Complete the quest Rodrigo's Revenge
- Complete Abby Lewis' quest chain
- Kill the Cottontail Matron rare elite
- Complete the quests at Carver's Harbor, Drustvar, ending with Cured Ham