I play my friends bison all the time and you do have options, but it is more like a rock paper scissor game than anything else.
In the middle of the screen, after a blocked scissors, bison can do cr. lk cr. lk scissors, which you can simply hold back and walk away from it, you’ll walk right out of range of his lk. Don’t try to ex messiah this, he’ll just block it, you’ll waste a stock, and if he has ultra 1 (which all bison’s should be using in this match up) you’ll eat a raw ultra unless you fadc backdash, which he’ll then punish you with a st rh.
He can do st. rh after a blocked scissors, which is also bested by simply holding back and walking away or you can get gutsy and use stand strong to beat it.
Or he can throw out another scissors, which you can beat by doing fierce tornado or a stand strong (these are both risky, but if you guess right once, it will help to stop bison from doing this later, ex messiah also works here, but you risk losing a stock because it will typically catch him in the air and only do one hit).
One of my main goals is the stop them from doing the cr. lk cr. lk, if you can, you get to jump away, jump straight up and dive, or ex messiah more.
The corner is where things get stupid:
You can no longer walk back, so you are forced to deal with the lk’s, it is in your best interest to just wait it out. As stated earlier, ex messiah should not be used against his cr. lk’s, you don’t want to jump because you will get hit by rh and then reset back into cr. lk games, and you don’t want to press a button because you will outright get stuffed. The best thing you can do is be patient, most bison’s will try and predict your jump and rh all on their own, giving you enough space to press stand mp, or try for a messiah. He will eventually push himself out of range, giving you just enough room to breath and get yourself out of the corner.
For this match you just have to realize that you will end up eating a lot of chip damage. As always, watch out for throw attempts. Crouch teching against bison is pretty good as long as you can get into the same rhythm as their cr. lk. strings. Just try and do some really late techs because he can mix everything up into cr. mk or st fierce.
And for Guy, I have been having a lot of luck with stand fierce. If he flips at you, stand fierce (the close version) will cleanly stuff him. As Gerjay said, you beat him on the ground pretty cleanly, taking away his air to ground options leave him at a heavy disadvantage. And if you knock him down, try doing a fairly high cross up dive kick against him, it will blow right past his ex up kicks on wake up for a free punish.