Hardest mate in 1 puzzles


M2
cxb6+ c5 Bxc5#
c6+ Qc5 Bxc5#
1.cxb6+ not possible, there is no proof that Black's last was ...b7-b5.
1.c6+ is fine, and mate next move.
For some reason, a crapload of useless pieces are planted at the board.

if the c7 pawn wasn't there white would have cxb6 e.p. mate
En passant is against the chess composition codex here, and in any case 1.cxb6 wouldn't be mate- 1...Qe7.
In all likelihood, this is yet another stupid post, not a real puzzle.

Just look al possible checks. you will soon find out. no mate in 1 is tough if you know that it is mate in 1

Black must play g2 because it is the only way to win the game
So, is 1...Nf2# illegal, or what?