Only 2 reasonable reasons come to my mind:
- To avoid stalemate (never happened to me).
- To convince your opponent to fall into a prepared trap instead of capturing the promoted pawn (occurred twice in all chess career).
There's a video Jerry uploaded to his channel that shows a very rare case in which ONLY the bishop promotion is correct.
Could someone find this video, please? I'm too lazy to do so right now...
1. Queen easily stalemates
2. For the challenge
3. They already have many queens
4. Or just trolling Stockfish! (that's me)
Here is a chess problem that goes even further: Depending on what the opponent promotes to you have to promote to the EXACT SAME piece to win. So if he promotes to rook you MUST promote to rook too, to win. Same for bishop :
http://timkr.home.xs4all.nl/chess/babs.htmlThere could also be no difference in mate speed between rook/bishop or queen, so the choice is irrelevant
As others have said, promotion to rook or bishop instead of a queen is done for avoiding the stalemate. In bullet games or even in slower games, if you don't have enough time and you are clearly winning(for example, you have too much pieces and your opponent has only a king to move) and you don't have time to check at each move whether your opponent's king has a free square or not, promoting to rook or bishop would be a better option.
Also, there can be rare situations where the moment you promote your pawn to queen, the game ends in a draw as your new queen blocks the only free square(s) of your opponent's king resulting in stalemate.
Oh! I didn't see that. Dr_King_Schultz, in his #16 post, has already shown us two situations where the moment you promote your pawn to queen, the game ends in a draw as your new queen blocks the only free square(s) of your opponent's king resulting in stalemate.
Btw, there are also situations where underpromoting to a rook / bishop is neccessary for the worse side in order self-stalemate and draw.
