It is not clear to me what happens when a Pawn is on 9th rank, and nothing of that color is captured yet. Is the move to 10th rank now forbidden? Or would the Pawn just stay a Pawn? (This could make sense to capture something.) If the move to 10th rank is forbidden, would it still check a King on 10th rank?
I think we should follow the Grand Chess rules for promote-by-replacement. A pawn cannot move to the 10th rank if there is nothing to promote to, but it can still give check. This would never happen in a real game anyway.
I think we should follow the Grand Chess rules for promote-by-replacement. A pawn cannot move to the 10th rank if there is nothing to promote to, but it can still give check. This would never happen in a real game anyway.