I spent way too long trying to figure out what Cozy’s next move could be.
I’d probably use c2 Rook to capture the Queen’s Pawn.
Bait Diamond to capture it with King, then shift the other Rook to check King on b2, forcing the King out to the center with a Rook and Queen side-by-side.
If she Castles instead, then I move Queen to d3, threaten Rook on f1, while also imposing on castled Rook and g3 Knight with Cozy’s Queen controlling lots of the center.
(I think the board was set up on the wrong tiles).
This should not be tagged as checkmate. Black is at a considerable advantage, but the position isn’t even totally lost yet for white. After forced Bd1 (the only way white has to protect against the black queen on b1), the white king can run up the e file and the game continues.
I do enjoy the idea that Cozy is a chess prodigy though.
Note that Diamond isn’t in checkmate yet: she can still move her bishop to d1 to block Cozy’s queen, then she might have the opportunity to castle in the next turn.
After this day diamond tiara learned that ponies who have chess piece as a cutie mark mean they are actually quite good at it. She avoided playing with them ever since.
Edited
Bait Diamond to capture it with King, then shift the other Rook to check King on b2, forcing the King out to the center with a Rook and Queen side-by-side.
Edited