The Aztecs:

The Aztecs have no stable or stable units. They rely totally on infantry. They are unable to build gunpowder units too. This is a big weakness. However, the infantry are created 15% faster than normal, which is helpful. All monk technologies are present, and every time a monk technology is researched all monks get +5 hit points ( 85 total ). Monks are be important for the survival of the Aztecs.

The Huns:

The Huns are a cavalry based civ. They do not have to build houses for the entire game. Because of this, they are great for traveling around and escaping from the enemy. The Tarkan is a great unit because it has the ability to destroy buildings quickly, escape, and attack elsewhere. In multiplayers the Huns will be good nomads. If there town gets destroyed they will be able to throw up a base quickly elsewhere.

The Koreans:

The defensive based civ. With the tower bonus, the Koreans will have good cities. The Warwagon is a good, quicker moving missile weapon that is good for any army to disrupt the enemy. The Turtle Boat, although slow, will be powerful if supported by quicker moving galleys.

The Mayans:

As with the Aztecs, no stable or gunpowder units. The Plumed Archer will be a stronger, faster foot archer. The economic powerhouse, the Mayans will be good for the resource fanatic.

The Spanish:

The generalist based civ, the Spanish are a pretty normal civ. The Conquistador, a mounted hand cannoneer, will be good for hit and run although it has a shorter range. The Missionary will be good for quick conversion and  can escape quickly if conversion does not go well.