Has an Olympic Baseball game ever ended 18-0?
Exactly once. On January 1, 1992, Cuba beat Spain 18-0, and no Olympic Baseball game before or since has ended that way. When it happened it was a scorigami, the first 18-0 in league history.
That makes 18-0 the 48th most common final score out of 87 that have ever occurred in Olympic Baseball. One point away, 19-0 has happened never and 18-1 has happened 1 times.