[Dilettante_Pro]

Проверяем по минимальному набору

var m = 3, w = 3;
console.log(m*(m-1)*w/2 + w*(w-1)*m/2);
console.log(m*(m-1) * w/2 + (w - 1)*(w - 2)* (m-2)/2);

var d = [["M1","M2","M3"],["W1","W2","W3"]];
var del = [], k=0;

for(var i = 0;i < 2;i++) {
    for(var j = i + 1;j<3;j++){
        for(var l = 0; l < 3; l++) {
           del[k] = d[0][i]  + d[0][j] + d[1][l];
           console.log(del[k]);
           k++;
        }
    }
}
for(var i = 0;i < 2;i++) {
    for(var j = i + 1;j<3;j++){
        for(var l = 0; l < 3; l++) {
           del[k] = d[1][i]  + d[1][j] + d[0][l];
           console.log(del[k]);
           k++;
        }
    }
}
console.log(k);