Ok I typed up a little Bison vs. Blanka.
The most important thing is to sort out your anti-air. Bison’s primary air defense is going air-to-air: climbing jump strong, vertical jump rh/strong, escaping jump rh, etc. This isn’t his only option, however - two other choices to keep in mind:
crouching fierce. If Blanka is eager to win an air-to-air clash with his jumping jab or short you can generally shut him down with this ground attack. You need a feel for the spacing and a read on your opponent, but crouching fierce is a good back-up anti-air.
run away. Psycho crusher underneath him as he jumps in. Or, if he’s trying to start a cross-up short trap use a slide kick to sneak away.
In a ground battle standing medium kick is ok. Keep backing up - it’s good to have a quick trigger finger on the scissor kicks and psycho crushers to catch him doing a slide punch or crouching roundhouse.
Like TRT says, cross up medium kick loses to reversal vertical ball. You can beat that ball from the front though. The jump kick has to be a little bit high (i.e. a shade later than “well timed”) to avoid a trade.
Fierce psycho crusher seems to be a decent option. Blanka can block and counter with a crouching fierce but in my experience it’s a little random. If you do one psycho crusher and he misses then another and he hits, the 6 ticks of life from the blocked crushers will add up to more damage than the one fierce punch.