ive actually done those levels a few times now, i used 2 different ways to do it, 1, try using sigfried with lots of hit points and defence with an ability to get more health either hp drain a or hp burst and then use his AT diagonal backwards and down with y, he will stab his sword through them and hits alot of the time, i used him with mitsurugi with the same atributes, another thing to look for is weather they can be knocked out of the ring if they can be thrown and can be rung out then use mitsrugis a+g throw and always do as much damage as you can while therer down. the other way i did it was to use yeung sun and just spam his forward y move to critical finish them. you will find that i you mix it up like i said you will get it sum rounds they will just punish you but wen u get it right you will tear through them. astoroth is normaly a safe bet but on this they take such little damage from hits , but they seem to take normal damage from attack throws. hope this helps dude. let me know if you need more detail.