The version of zPets that has a UI has been renamed and moved to zCombat, if you are looking for that please go to https://www.curseforge.com/wow/addons/zcombat.
zPets is now just a pet tracking library for other addons to use.
zPets API:
zPets.RegisterPetEvent(event, callFunction)event - requires "OnSpawn" or "OnDespawn" callFunction - the callFunction will be given the petGUID as an argument. This petGUID can be saved and used to ask zPets for various pet data
zPets.IsPetTypeActive(petType) petType - takes a name of a pet, "Wild Imps" or "Dreadstalkers" RETURNS - true/false
zPets.GetPetName(petGUID) petGUID - takes a petGUID that is given when using 'zPets.RegisterPetEvent' RETURNS - petName
zPets.GetPetDurationInfo(petGUID or petName) -- If given a petGUID it will give specific data to that pet, if given a petName it will return the first one it finds, which isn't always going to give accurate information, I would only use if you know only 1 of the pet will be out. petGUID - takes a petGUID that is given when using 'zPets.RegisterPetEvent' petName - takes a petName RETURNS - petDuration, petDurationRemaining, EstimatedExpirationTime
zPets.GetPetEnergy(petGUID) --Note: this is only really accurate for Wild Imps, cause it's the only one setup to track combat events to keep track of energy. petGUID - takes a petGUID that is given when using 'zPets.RegisterPetEvent' RETURNS - petEnergy
zPets.PrintTheorycraftingData() Prints to chat data on guardian recast times to help figure out their min / max recast times.