I have been hearing from everyone how Moira doesn't have any hard counters, but I believe I have found 2 characters that are hard counters. Doomfist and Roadhog, can both stop Coalescence instantly.
I'd consider tracer somewhat of a counter because she can pulse moira while she's using coalescence and she can't fade away like she can normally do.... well only when it's a good tracer who can charge her ult fast