Zoo has been a deck in many magic formats for a long time, even before Wild Nacatl and Bloodbraid Elf you could be Tribal Flaming people and making aggressive gold strategies work with a green base and its good mana fixing. Typically Zoo is Naya however it can be done four and five colour, can add black or blue, and now with Tarkir block you can pretty much do any three or more colour Zoo deck so long as it is base green. There were a couple of good blue things pre-Khans but they tended to be tricksier and less robust and so less worth bothering with. The Temur clan is all about beefy things and gives lots of options to a Gru aggro list.
Typically aggro decks have had to employ various strategies in order to compete in the powerful and diverse cube meta. Historically just making a dork each turn with good aggressive stats is one of the easiest things to beat in cube. Removal is good against you, mass removal is killer against you and every two for one they get against you is crippling. Aggro decks had to go under, go over or throw redundancy out the window and play plenty of disruption and removal of their own. By going under I mean playing such a low curve that you can have pretty much closed out the game before Wrath of God can end you. By going over I mean playing lots of burn you can start to aim at the dome when you have got as far as you can with dorks or playing lots of evasive threats. The final option involves playing things like Path to Exile in your zoo deck, Armageddon in your white weenie or even countermagic in your beatdown deck! Slowly this became less necessary as threats became more persistent and more diverse. Being able to play several planeswalkers that are good threats as well as man lands, gods and creatures that need to be killed twice, exiled, dealt with without targeting or dealt with without using damage all stretch control decks too thin. For a while pure curving beatdown decks have been tier one in cube. It seems that now they are leaning less on planeswalkers and dorks that leave things behind after death than ever and just playing fast hard hitting threats. Why pay 3 mana for a 3/2 that comes back as a 2/1 when you can get a 4/4 is now a reasonable question.
Birds of Paradise
Rofellos, Llanowar Emissary
Courser of Kruphix
Surrak, Caller of the Hunt
Shaman of the Great Hunt
4 Sac lands (3 pain, 1 CitPT)
Kessig Wolf Run
Finally, for the odd choices we have Flamewake Phoenix and Fauna Shaman. Both weasly 2/2 bodies that are more utility than beatdown. Obviously they come as a bit of a pair but also have some suitable synergies throughout the rest of the deck such that they are good. Fauna Shaman is just another cheap body that it fine to cascade into, fine to get in for a few free damage and then get involved in the alpha strike and fine to just help you curve out with as a two drop. Beyond this it can get you card and mana advantage with Flamewake Phoenix and Vengevine if you need it as well as finding you the dorks you most need. Broadly you don't want to be activating it, you would rather it was just a Grizley Bear however when things do look a bit dicey or you need something specific you are very happy with your little Bear having a slot. It is insurance and options and it doesn't cost much at all for that, has good synergy and is easily paid for by the high power level of your pure threats. Likely I would run Tarmogoyf in the place of this card, a tired and tested winner but not a card I can easily rely on with this deck to be big at all early and with all the delve about at present poor old Goyf is finding that he is getting shrunk a lot more than before. Flamewake is least suitable becuase of the RR cost on a three drop, otherwise he is fine in the deck all be it not the most exciting. A little bit more flying in the deck is really helpful but I could happily have played Yasova Dragonclaw in that slot and they are fairly different implying that there is no real need of either.
Ancestral Vision and Sarkhan Unbroken both have appeal in the deck however again I favoured consistency over raw power and went without either. Ancestral Vision is one of the loveliest things to cascade into as well as being a fine use of mana early. The problem is you don't want to lose out on tempo to make the Visions when you have that option and so you have cross purpose cards. Additionally off the top late the Visions, as with a lot of decks, is just too slow to really be helpful. Sarkhan Unbroken is silly good but being five mana, not a dork, and not being able to do damage right away he seems not the best choice for this build.
Boon Satyr and Ghor-Clan Rampager are huge in the deck. They are decent threats with the creature type in their own right, both providing ferocious, having decent stats for the price and a flash/trample sweetener. More importantly however they are combat tricks that allow you to scrimp on removal effects and unflinchingly turn your men sideways into all sorts of horrific looking blockers. Shaman of the First Hunt and Surrak, Caller of the Hunt got their first trial in this deck and were both very impressive, great ambassadors for what the deck is trying to do. Surrak was probably better overall as he does more for less mana and more on his own but that is down to the deck, there is no denying that Shaman is the more powerful card overall.