I can only offer a mostly Ken perspective.
For Bison, I try to stay mobile and look for the range where he likes to scissor. Lk Scissor has a specific range, and outside of it he has to use the other ones, which are unsafe if he hits twice and can be focused otherwise. Staying either outside or inside the perfect lk scissor range is the goal.
That said, lk scissors is less scary than it looks. It does like 70ish damage IIRC, which is measly in this game. Sure it knocks you down, but you shouldn't panic on that, it's not like Bison is a vortex character. If you get put in the corner, and you will, look for what Bison likes tlo do to keep you in there and adapt appropriately. In almost all cases it is best to wait for him to act. Jumping badly or reversaling immediately = you eat unnecessary damage and is the rare case where you can get stunned by bison. Headstomp and Devil's reverse can be both beaten by jump back attacks or avoided by moving forward. Don't pressure Bison too hard on knockdown when he has meter, but when he doesn't jump on him inside of the range of his St RH until he proves he can anti-air you consistently. His AA is weak or pre-emptory without meter. Don't walk around too much because of slide. Outfootsie him, get the life lead somehow and sit on it.
With Balrog, again staying outside of the range of his lp punch is a good idea if you can. Unlike Bison Balrog has good AA so don't jump too much when he has charge and especially when he has ultra. He's a hard character to beat for a lot of characters, including Ken =(. Don't get frustrated by rush punches and react to TAPs if you can with DP's or similar moves. Counter rush punches by mixing up neutral jumps, focuses, and using multi-hit or armor breaking moves. His headbutt sucks as a reversal and loses to low meaty attacks so use them but beware of his armor rush punch as a possibility too.