I'm still a firm believer than sonya beats cyrax;
MITDJT could probably explain it better than I can, though.
i actually have played this mu with my bro alot, and sonya has the slight advantage. I'll list some things:
* her divekick will cause him issues: unsafe on block yes, but when timed properly/used properly it works well. If a rax tries to d4 and u do a divekick, that's a full combo for you. It also prevents him from knowing when to pokek out of her pressure. If he decides to do a net and you jump, full combo off the divekick.
* her pressure: cyrax has a huge hitbox and she can abuse it with her standing 1s at times and her d4 ms pressure will help sonya build good meter just in case she gets caught by a net. she can mix in her f4 and grabs at time as well.
* her projectile: super swift and safe. cyrax can barely get a trade off bcuz of how fast her projectile is. It is fast enough to hit him while he throws a bomb out as well.
*armor kartwheel: can blow up any crossup jump attempt he goes for and punish him if he goes for a deep jik. Blows right through the net as well, so cyrax has to be careful.
* her uppercut: if he tries any special way to jump in or whiffs a high hit, smack!!! that d2 will hit him everytime.
*footsies: her standing 4 works great and leads to great dmg, her divekick, d4, and sometimes her standing 2,1 can all be used to give rax issues.
Overall rax can still hold his own bcuz of all the tools he possess and one mistake for her can end the fight for her. Also he can AA grab an ex kartwheel when he baits it and if he gains the lead, he can turtle her out well. To get out of pressure, he can use d1 to ex ragdoll since that is safe and pushes her back. He can AA grab all jump ins from sonya/ her divekick. If sonya whiffs a d4 and he does a net, bad news for her and she has to be careful what she does when dem bombs come out. His d4 buzzsaw will work as well and his buzzsaw in general must be respected, but he must be careful not to whiff it bcuz that'll lead to a full combo for her. His command grab will work great for him since she can't crouch block it and duck it unfortunately like sektor and mileena for some reason.