"Stanch ally" is a phrase used to refer to someone who is a dependable and reliable supporter. If you want to use synonyms for this phrase, there are several options you can consider. Some other phrases with a similar connotation might include "faithful companion," "loyal confidant," or "steadfast friend." If you're looking for specific single-word synonyms, you might consider options like "devoted," "dedicated," "committed," or "reliable." No matter which word or phrase you choose, the key is to find a way to convey the sense of trust and dependability that is conveyed by the phrase "stanch ally".