What's the rarest kind of checkmate?

Just because you've seen it happen in some selected games doesn't mean it's not rare or it's not the rarest, highlighting matches doesn't mean anything, you'd have to provide actual statistics and numbers for anyone to demonstrate exactly what is the rarest checkmate. Chess.com maybe be able to tell us what is the rarest checkmate at least online.

Maybe. But the question is what is the rarest. The fact castling checkmates are easily found in high profile games indicates that it happens with some frequency. We've seen it.

Something more rare would be something we havent seen, or have seen even more rarely. Some of the checkmates listed, like KB vs KB, KN vs KN, K vs KNN, or even the en passant discovered bishop checkmate are likely to be much more rare. Has anyone ever seen one?

It's likely there aren't many statistics on what is the rarest checkmate. But just from experience and what we've all seen, we can be pretty certain something like the KN vs. KN checkmate is going to be more rare than a castling checkmate.

What are you talking about, you're referencing Top Level games, like 0.00000001% of the chess world who can't relate to that level of mastery and where the vast majority of games are NOT played, it doesn't mean anything overall. There's also short castling and long castling. I'd imagine it's enpassant but castle checkmate is still rare.

En passant on the center files (Because center pawns don't survive till end) checkmate with a discovered check by bishop.

Yes, castling checkmate is rare. But the question is what is the rarest. Many of the suggestions listed are rare. But from recorded games we know that castling checkmates happen with some frequency. Top level games only indicate that it's happened even with very good defenses. Meaning often it was forced. Imagine how many times it happens with unwitting amateurs.

How many recorded games end with a KN vs. KN checkmate? I've never seen or heard of one. It would be an incredibly rare set of circumstances to have a forced KN v KN checkmate. It would have to involve a series of specific forced captures on top of the kings already being in a corner. If we don't have reliable statistics, then we have to make a best guess based on what we do know.

Good point about long and short castling. That certainly makes castling checkmate less rare than it could be if it were just one side. Rosen performed a castling checkmate where the enemy king was only about 3 squares from his home. Not down in enemy territory. So there are MANY positions where this could be a possibility.

i have done long and short castle checkmate

Just out of curiosity, have you ever performed a KN v KN checkmate? Or seen one?

The rarest kind of checkmate was (it’s no longer possible due to changes in the rules) an e-pawn promotion to a rook followed by 0-0-0-0-0-0-0#

Nowadays it’s a long string of checks where the opponent is forced to run their king to your back rank followed by a 0-0#, as the circumstances necessary for this to occur simply don’t happen between good players ever. Ironically this is extremely common in bughouse.

Since the question is what the rarest kind of checkmate is, we could say it was one that involved a long series of forced checks, followed by a smothered knight mate. It happened in the early 20th century between two amateurs. It's never been repeated, it only happened once in that order. So by definition, it is the rarest kind of checkmate.

I could see how there could be millions of examples of the rarest kind of checkmate.

no castle checkmate is common i think its bishop mate

no

En passant mate by use of rook! Here's mate in 2.

cool

the peaceful checkmate...