Promotion is done based on the piece type, so if the Joker is not amongst the promotable pieces, it will not promote. Only moves are immitated.
Because you have two different kinds of Pawns the test for it becomes complicated. In any case the destination square must be empty. But then for normal Pawns diagonal moves must be excluded, and for Berolinas the straight moves. So omething like
Promotion is done based on the piece type, so if the Joker is not amongst the promotable pieces, it will not promote. Only moves are immitated.
Because you have two different kinds of Pawns the test for it becomes complicated. In any case the destination square must be empty. But then for normal Pawns diagonal moves must be excluded, and for Berolinas the straight moves. So omething like
if(board[toRank][toFile] & 511) { if(pieceType == 1) return (toFile != fromFile); if(pieceType == 2) return (toFile == fromFile); }