Well with Rog I think you can play a modified version of your regular zoning game. I want him at like 3/4 screen and I always try to have a fireball hanging out there. If I see him do tap or ex rush through a fireball, short/forward slide on reaction stuffs the tap and the second hit of the ex rush. If you hit with the end of forward slide, link to down-back+jab xx whatever, and if you hit with short slide cancel it right into whatever, or mix that up with throws. It’s definitely hard to antiair him, but I find that max range down-back+jab and down-back+fierce will usually work, and slide always beats an early or regularly timed jumping attack.
If you knock him down right next to you and you don’t want to just teleport far away, you can do very early down-back+short on him all day because the last frame of that move + its recovery is less than any of his wakeup moves, from headbutt to super to ultra. This is kinda hard to time and I still mess it up a bunch, but it really is worth practicing.
With Chun, I think you need to be aware of both sliding under fireball and how to antiair her jump-ins. Down-back+fierce and down-back+strong beat or trade with her far jumping fierce; back+strong and slide beat her close jumping fierce; back+roundhouse beats far early jumping roundhouse; back+strong beats close early jumping roundhouse; jump back instant back+strong and back+fierce beats late jumping roundhouse; and back+strong beats far jumping short and close jumping short. I think it’s really hard for Chun to jump at you.
Once Chun figures this out, she’s going to try to get in with fireball to walk-up and flying overhead instead, and that’s not that easy to deal with. If the Chun player is dumb enough to throw a fireball where you can punish it with slide on reaction, then awesome, but that’s not likely to happen too much. He’s gonna walk out of range and do it then instead. From there, you just have to learn which of your normals beat or trade with her’s and guess or react to things like her overhead and crouching roundhouse. If she gets in, then yeah, it’s really hard for you to deal with her and you’re probably gonna take damage, but oh well, that’s how it is with almost all of Sim’s matchups.