Online, the only answer I found was never ever stop holding downback when he's on the ground, and never do use stinger aim outside of 2s > hs stinger. One you land a knockdown your oki game is better than both his own and his wake up options. A lot of his big pokes he fishes with also destroy projectiles, so you mostly just have to play patient and accept that 2s is the only poke you have.