quadratic checkmate of quadruple disambiguated knight checkmate of pq
What's the rarest kind of checkmate?

double disambiguated bishop chekmate, that's the rarest
Rumor has it that it's happened at least once. So it can't be the rarest.

I've had a promotion to knight checkmate once, ever. It was a game with the guy who taught me to play. He had a massive material advantage, was busy mopping up my few remaining pieces, and didn't much care that I was marching a pawn towards his back rank, because his king was so securely walled up by his own pieces that there was really very little damage a queen could do.
"Checkmate."
"Don't be ridiculous, how could that possibly be checkmate?"
"That is not a queen, that is a knight, and that is checkmate."
I have savoured the look on his face for thirty years.
[Removed - DB]
what is his FIDE??

I've had a promotion to knight checkmate once, ever. It was a game with the guy who taught me to play. He had a massive material advantage, was busy mopping up my few remaining pieces, and didn't much care that I was marching a pawn towards his back rank, because his king was so securely walled up by his own pieces that there was really very little damage a queen could do.
"Checkmate."
"Don't be ridiculous, how could that possibly be checkmate?"
"That is not a queen, that is a knight, and that is checkmate."
I have savoured the look on his face for thirty years.
[Removed - DB]
what is his FIDE??

I've had a promotion to knight checkmate OF A BI*************** once, ever. It was a game with the guy who taught me to play. He had a massive material advantage, was busy mopping up my few remaining pieces, and didn't much care that I was marching a pawn towards his back rank, because his king was so securely walled up by his own pieces that there was really very little damage a queen could do.
"Checkmate."
"Don't be ridiculous, how could that possibly be checkmate?"
"That is not a queen, that is a knight, and that is checkmate."
I have savoured the look on his face for thirty years.
[Removed - DB]
what is his FIDE??
double disambiguated bishop chekmate, that's the rarest