It’s an incredibly up-hill battle and even against a shit Blanka Hawk has to be on top of his game. On GFWL (which I mainly play) I’ve played a few of the top ranked (I know it’s not overly important but y’know) Blankas on there with various degrees of success.
Not unlike Sim, Guile and Sagat and other match ups you need to play patiently, if the Blanka is just going to spam balls all day while laughing because you’re seemingly unable to punish it start trying to bait them out with jump back splash which beats most/all horizontal balls clean then you can obviously follow up with s.MP > lp.Tomahawk. Additionally, if they’re being predictable and throwing full screen balls you can punish with Tomahawk and Condor Spire (provided it is from the full screen, otherwise they’ll catch you in the start up and you’re almost guaranteed to lose).
The other thing that Blanka will probably use to try and catch you out is the jumping and hopping shenanigans where Blanka will constantly try and cross you up with j.MK and hops and will either try and go for a tick throw or a basic combo into lp.horizontal ball which puts them at a safe distance. There’s not a whole lot you can do to stop it, you have to just stay calm and not try and mash out SPDs or Tomahawks because they’re incredibly likely to fail. However, Thrust Peak and st.MP are really handy tools in this situation if you can time them right. It won’t give you a situation where you’re able to score massive damage but it will give you some damage and relieve some of the pressure.
The real problem is once you’ve scored the knockdown your options are reasonably limited because Blankas wake up options tend to beat everything Hawk does, practise the safe jump splash that Ponyo has in his video or just try safe jumping, most Blankas will either wake up with an Up-Ball or with Electricity, if he wakes up with Up-Ball and you’re in the middle of the screen there’s not a whole lot you can do except try and punish with st.HK, in the corner you can sweep for the knockdown.
I’m not as experienced as some of the other players in here, but my general game plan is to try and bully Blanka into the corner, score a solid life lead then back off and try and bait and punish balls. I use Ultra 2 in this match, if your reactions are good and you’re able to tell the difference between which strength of ball Blanka is throwing out you can beat it with U2 and it’s also a good punish for Blanka’s U1.
Again, this is all things I’ve learned from my own experiences playing and there might be some more solid technology I don’t know about that the other guys might be able to shed some light on. I have a couple of replays on GFWL against a few Blankas that I’ll try and upload as soon as I can get a good stable frame rate on Fraps with. But I hope this helps in the mean time :]