Durán's Historia de las Indias de la Nueva España attests to what is undoubtedly the largest army raised in the pre-Columbian Americas, 400,000 troops. The inciting incident leading to the massive army was the murder of Aztec emissaries sent to "ask" for emery (for lapidary work) from the cities of Quetzaltepec and Tototepec. Giving in to this request would have been tacitly agreeing to a tributary relationship, hence the murders.

According to Durán, Motecuhzoma Xocoyotl ordered that an army march from Tenochtitlan, "leaving only the old and the weak, the sick and the children.. So many men went to this war that they seemed to blot out the sun. There were more than four hundred thousand soldiers...."

This is probably an exaggeration, as Durán was wont to make, and the 400K number is a clue to this, given the vigesimal counting system. The massive army, however, would have been justified as the two target cities were notably fortified with walls and defenses. I write a bit more about that here.

Still sticking with Durán, we have a more commonplace number of troops during the invasion of Mechoacan, which is supported by other sources. The Aztecs had three xiquipilli (8K man divisions), but were outnumbered as the Tarascans had 40K troops. Other sources put this as more like 32K vs 50K, but regardless this was a massive battle (and massive Aztec defeat).

Other massive troop mobilizations are attested to in Durán and Díaz del Castillo who relay accounts of an Aztec force of ~200K being raised to attack Coaixtlahuacan. This is, again, probably an exaggeration, but the enormous numbers which could be mobilized is attested to in by the contemporaneous account of Cortés, who stated he had 100K Tlaxacalan and Acolhua troops backing his <1000 Spanish in the Battle of Tenochtitlan.

You may find interest in this: https://www.reddit.com/r/AskHistorians/comments/3g8fp5/do_we_know_anything_of_large_scale_native/