Here's my post from the The I am Stuck Thread
Got it, finally. Here's what I did:
For all the ninja waves I would just parry each attack then do a charged focus X attack on each one.
Kunoichi I parried each attack then did the A, X move to throw them into the air and cut off their legs.
The big guys... These guys are hard since there's 2 at a time and they stick together. I ran in on the one that made it down the stairs first and just XXX, YYY him over to the edge and knocked him off. Then just attacked the other one till he died. Repeat for each wave. Be careful when pushing them off the edge though that you don't fall off too. This happened to me on the last wave of big guys 3 times.