Were there ever any Indigenous Americans who fought alongside the American or British armies during the revolutionary era? ?

Natives fought on both sides during the Revolution, just as some fought with the British and some with the French in the French and Indian War, and during the War of 1812, natives again allied with both sides.

In all cases, whatever side natives chose to support, they did what they thought was in their own interest. 

Your revolutionary war I don't know much about.

War of 1812 when the USA invaded Canada, a definate yes.

"Tecumseh organized an Indian Confederation allied with Britain as repercussion for American attacks"

https://www.nps.gov/articles/courting-victory.htm

Here in Canada, indigenous people fought both with and against the British (there were many warring tribes to choose from).  However they tended to side more with the French than the British for various reasons.  I imagine it was similar in the USA.

The Stockbridge Militia was a Native American military unit from Stockbridge, Massachusetts which served in the Continental Army during the American Revolutionary War. This Massachusetts militia unit was composed mostly of Mahican, Wappinger, and Munsee from the Stockbridge area. While most northeastern tribes, such as Joseph Brant's Mohawks, aligned themselves with the British, the Stockbridge tribes cast their lot with the colonies. Led by Jehoiaikim Mtohksin and Abraham Nimham, they were the first group of Native Americans to fight for the cause of American independence during the Revolutionary War.

Yes there were, the Iroquois confederation of 6 nations fought as allys of the crown because they were promised that after the war was over, the colonists would be driven out of Iroquois territory and not allowed to return. That was a great incentive for them. The Algonquins, who were enemies of the 6 nations, aided the Americans because it was in their interests to defeat the Iroquois league.

yes there were