In the corner you can get well over 400 damage by just doing cr.mp > dash > cr.mp over and over, at the end of the combo you can do a mantis slash and then link it into ultra 2. I think thats what nemo uses most often but you rarely see yangs using seiei enbu because of the cool resets you can do with fadc...
Midscreen you can do cl.fp > teleport > cl.fp repeatedly but im not sure of the damage on that one, might be rubbish
I kinda went back to Ryu because im weak lol but Yang is great fun.
Edit: You can also hit confirm ultra 2 from a seiei enbu overhead!