An Iroquois army tends to be more varied than the other Native Americans, since they can use infantry, cavalry and artillery in their attacks. They are more like European civilizations than the other native civilizations in that respect.
The Iroquois can pursue any route they would like in-game, another factor making them similar to the Europeans. They can Boom, Turtle (possessing two Extensive Fortifications cards), or Rush as they choose.
The Iroquois siege is effective; the Ram can reduce a town to rubble, the Mantlet has enough hit points and resistance to act as a screen, and the Light Cannon is good against both units and buildings. The Iroquois deck has a few cards that can improve their already-impressive siege weapons.
Defensively, the Iroquois are the only civilization with access to the Extensive Fortifications 2 card, allowing them to build up to 21 War Huts. With the Germans as an ally, they can effectively transform their Town Center into a makeshift Fort via the Great House, Town Dance, Oneida Support (10 Villagers are the exact amount capable of boosting a town center's damage), and TEAM Teutonic Town Center cards. This increases the damage and durability of the town center dramatically.
The Iroquois forces suffer from two glaring weaknesses. The first is their cavalry, which is quite unimpressive, meaning that they're doomed to either be slow-moving or weak.
The other is their navy, which not only lacks anything to match the heavier ships, like the Aztec Tlaloc Canoe, but they are also the only civilization to lack the Admiralty card - meaning that their navy will most likely be smaller than the enemy force. A few Privateers, combined with the Water Dance from the home city, can be the rescue.