Adding further to what Phoenix posted, one big weakness for both Kyo and EX Kyo is that their j.D always whiffs on crouchers which makes it a really bad move in this game where it used to be amazing for approaching from a jump-in while also air-to-airing. Kyo lost this while the majority of the cast has a move that covers that horizontal and vertical space in one go. What this amounts to is that if you can stay just outside of Kyo’s j.C/j.2C/j.CD range you can force him to land on a sweep, dunk onto a fireball, or you can neutral/forward hop and tag him with a good air-to-air. You can also try feeling out their desperation when they get into range and then DP them, but if they’re good footsies and twitch baits you wont get to DP their hops very often. This is why the EX Kyo mirror is filled with a lot of nothing since neither can get close enough to safely j.2C without eating a rekka or DP or having someone backdash j.2C to reset the spacing.
If you can stay outside Kyo’s optimal hop range, anti-air his jumps, and stay active enough to discourage him from running forward into peak range then all you’ll have to deal with is a fireball/rekka which isn’t much if you just block since you’ll gain more meter anyway and he generally wont be plus many frames from this. Of course, Kyo’s footspeed is so good that he’ll inevitably get in if you give him enough time, so lay on the hurt while poking him out or AA him then go on the offensive from the reset/knockdown. Out-space Kyo, rush him down, or prepare to eat j.2C and j.CD.
And lastly unless Kyo messes up while in HD or is about to guard break you, don’t GCCD. Really you should only GCAB against him if you expect a blockstring to end with a fireball (or vs EX Kyo, any corner blockstring into rekka or you could try rolling a chain into f.B). Otherwise block and look for a way out, especially vs EX Kyo since he’s gonna safejump so all day in the corner.