At this point in Shadows over Innistrad Standard I am getting ton of enjoyment out of looking into unexplored territory. There haven't been too many successful Allies decks, as many have dismissed the creature type as a Limited archetype only.
Humans is the most popular tribal deck in Standard, but that doesn't mean that another tribal deck can't exist. In many ways this deck reminds me of Bant Humans, but with a different set of tools. Here is the current list:
Many of these creatures have seen little to no play in Standard, and when playing them opponents will be left dazed and confused. Gaining life and then pumping creatures with a Serene Steward off a Collected Company is a beautiful feeling. This is the type of deck than can take a tournament and metagame completely by surprise. The synergy here is at an all-time high, in fact there might be more synergy here than any other deck in Standard! Each card is part of a bigger puzzle.
This list is mine, but I admit there could have been cards or interactions that didn't occur to me when building it. It is intriguing to think that the deck can compete against the best decks in Standard, and this may not even be the optimal build! However, this build is the general direction that Ally decks that want to be competitive in Standard should take. There are plenty of early creatures to play but the deck doesn't really get the engine going until around turn four. This is why Humans is the most difficult matchup. The key is we don't want to be forced to chump block before deploying the cards in our hand.
Most linear, aggressive creature-based strategies are vulnerable to mass removal. While this deck is somewhat scared of sweepers it is also very resilient. March from the Tomb can completely Nullify a sweeper; when all of our creatures return from the graveyard, they can potentially provide some Kalastria Healer triggers to boot. March from the Tomb is the most mana-intensive card in the deck — you want it to be the last card in your hand, and only gets cast after a lot of creatures have died.
At the moment, in Shadows over Innistrad Standard, most decks have lots of creatures. In all of these matchups the goal is to get one of our flying threats into play and have it live for a turn or two. At that point it becomes easy to set up defenses on the ground, and even if that means chump-blocking, it becomes pretty easy to win the race. The few removal spells we do have are meant for Ormendahl, Profane Prince and Archangel, Avacyn against W/G Tokens, the best deck in the format, so beating it is no small victory.
I don't expect Allies to be popular, but that doesn't mean it isn't worth a try! The deck is fun to play with, and a change of pace can be good. In fact, if the W/R Humans deck wasn't as popular as it is, the deck would be in a great position in the current metagame. Even the Humans matchup is winnable, and it is possible there should be a fourth Languish in the sideboard.
Thanks for reading,