In 8x9 chess: Same as standard Chess
In 8x10 chess: Pawns can move two or three squares on their first move. If they already moved one square, they can still move two squares on the second move. (Left)
In 8x11 chess: Same as 8x10 chess
In 8x12 chess: Pawns can move two, three, or four squares on their first move. If they already moved one or two squares, they can still move two or three squares up to the middle of the board. (Right)