The checkmate can be one of the checkmate patterns, or be a mate that doesn't match any of the patterns.

Examples

Checkmates with three or more pieces often don't follow a fixed pattern.

White can checkmate with Ng5#.
The knight also guards the escape square e6, and two other pieces are helping: The rook on h8 guards the escape squares g8, f8 and e8; and the queen on d4 guards the escape squares f6 and g7.

Black can checkmate with Qe1#.
Two pieces are helping: The bishop on g3 protects the queen, and the knight on c5 guards the escape square d3.
This is similar to Damiano's bishop mate, but the king is not on the edge of the board.