Concept
Ally Rally is an all out aggro deck that tries to win as rapidly as possible by attacking with a swarm of synergistic creatures.

Game Plan
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.