Pinch-hitters and relief pitchers

[JEFFFESPERMAN]

When Hal "announces" a pinch-hitter, does that batter always bat? Likewise, when Hal brings in a reliever, does that pitcher always face at least one batter? For some odd reason, I've never thought to check for this when reading box scores.

[Eddie E]

As in real baseball, relief pitchers brought in by HAL must pitch to at least one batter. On the other hand, HAL can sit a pinch hitter when a different reliever is brought in.