With Gnomes now making Hunters the second class to be available to all races, they are bringing with them the new "Mech" pet family. These will be pets that, if I'm not mistaken, will actually be classified as Mechanical. If you're not a Gnome Hunter (and given that Legion isn't out yet, you aren't) you might be wondering how you gets your hands on such a glorious thing.
There will be Mech pets other than the one that Gnomes start out with, but taming them will require a couple prerequisites.
First off, most Hunters will need to get a special item from Engineers called a Mecha-Mind Synchronization Fluid to enable the taming of Mech pets. However, if you're a Gnome or a Goblin, you can skip this step - Goblins and Gnomes are already very much in-tune with robots and other mechanical stuff, and thus need no such fluid.
The pets, other than the Giant Mechanical Rabbit that Gnomes begin with, will all have puzzle-like challenges associated with them. An example they have was the need to create a special punch card in Gnomeregan to get access to a Mechano-Strider.
I don't know if these will be quite as complicated as the Gara "quest chain," (which didn't actually include any official "quests," and was seriously obscure if you didn't use an online guide,) but it should be a nice challenge for those who want to have a robot fight for them in battle. (My Dwarf Hunter, who is a Gnomish Engineer, will certainly be working on this.)