Sagat can die to Ryo much like he dies to Yuri.
RC 100 Blows beats anything Sagat has, so why not RC Crazy hands? 'Nuff said, Sagat loses.
In P/S/K grooves…
P - Jump-in parrying will be your best friend, that and maybe tk air fireballs, but those aren’t as good as Akuma’s or anything. Ryo is a damn rock, and his jab uppercut should have the same effect as Ken’s does; kicking Sagat’s ass every time he throws a fierce or RH. Really, Ryo’s main problem is Sagat’s fireball and anti-air, and age-old combination, with age-old strategies to beat it. Besides, Ryo has his own fireballs.
S - I don’t believe I’ve ever played S-Ryo, so this is Theory Fighter. The hardest part is limiting dodge to a rare use, used only when needed. Make sure you know Ryo’s dodge attacks, and God forbid I know them so someone else should answer. Ryo’s Desperation fireball super should be a great asset that could even turn a match around, but this can’t be so abused vs. some grooves.
K - JD that shit and gain life. Try to keep the game at distance and show the Sagat what kind of patience Ryo has! I would play really defensive, victory is quite possible with patience. If you get rushed down, then just remember that he has jab uppercut to outprioritize basically anything.
Even if you can’t RC, Ryo can be the victor in skilled hands.
Any character is worth using.