The King and Queen cannot go out of his or her castle. To accommodate for promotions and dropping, it is best to use flat pieces that can be flipped, and also pointing like an arrow. An example is a Shogi playing piece, with one side denoting the regular piece and the other side the promoted piece. Pawns move one square forward. Promoted pawns move any number of squares horizontally or vertically.
Bishops move one square diagonally.
Promoted bishops move any number of squares diagonally. Knights move one square horizontally or vertically, then one square diagonally, like a knight in XiangQi, which means it can't 'jump'. Promoted knights can 'jump' as in usual chess. Cannons move any number of squares horizontally or vertically, but capture over another piece, like a cannon in XiangQi. Promoted cannons can move diagonally.