Ally Rally is an all out aggro deck that tries to win as rapidly as possible by attacking with a swarm of synergistic creatures.
The deck tries to rapidly put on the battlefield as many small creatures as possible and to relentlessly attack while leveraging the synergies among allies.
Allies use a variety of ETB or other abilities to pump or otherwise grant combat relevant abilities (e.g First Strike, Vigilance, Trample) to other fellow allies, until the opponent is no more...
The plan is simple and straightforward with very little room for variations.
The deck is almost entirely based on creatures (including spells that generate creature tokens) with few non creature spells that can either enhance your creatures or eliminate the opponent's creatures.
I look at this deck as composed of four packages:
allies specialists
allies soldiers
utility
removal
is where all the allies with enhancing abilities belong. These can be divided in two sub-groups: those that grant abilities to all other allies on the battlefield when a new ally enters the battlefield and those that have other types of abilities.
Examples of the first sub-group are: Kor Bladewhirl, which grants first strike to all allies, Tajuru Warcaller (+2/+2), Hero of Goma Fada (indestructible), Lantern Scout (lifelink), and Makindi Patrol (vigilance).
While in the second group we find Veteran Warleader, which grows with the number of allies on the battlefield and can get first strike, vigilance or trample by tapping other allies, Kazandu Blademaster, which gets +1/+1 counters, and Munda's Vanguard, which can tap an ally to put +1/+1 counters on all allies.
The allies specialists package takes between 12 and 18 slots.
has the sole purpose of increasing the density of the allies in the deck and to provide bodies to trigger the specialists or to be enhanced by the specialists once on the battlefield.
This package can also be subdivided into two sub-groups: vanilla and vanilla-like creature cards such as Expedition Envoy (2/1 for 1 mana), Kor Castigator (3/1 for 2) and ally-tokens generating spells like Raise the Alarm (two 1/1s for 2 mana), and Allied Reinforcements (two 2/2s for 4 mana) which put multiple ally bodies onto the battlefield in one shot.
The allies soldiers package can include up to 16 cards. In general the deck tries to have 25-30 ally cards in total between specialists and soldiers.
occupies a small portion of the deck and normally focuses on pump spells like Travel Preparations, the Prepare side of Prepare // Fight, and Captain's Claws, which also generates more ally soldiers.
The utility package normally takes 3 to 6 slots.
is limited to 4 to 8 slots, and normally includes a play-set worth of pacifism-type enchantments like Pacifism itself, Demotion or Compulsory Rest, plus sometimes the Fight portion of Prepare // Fight.
Ally Rally is a mono thematic deck that focuses on going wide with allies to assault the opponent from the start.
The deck works well when it's on the offensive. However, if the opponent manages to turn the tide and apply some pressure, the deck can get in trouble pretty soon as most of its synergies work much better on the attack than on the defence.