Well, this stuff isn’t exactly “Oki” per se, but these are ways that you can mess with the opponent’s wake-up so that you will be in range to continue some kind of pressure no matter how the opponent gets up from a knockdown.
With Ken, if you do his forward throw, then immediately forward jump, if your opponent rolls they’ll be rolling in the same direction that you jumped. And if you do a delayed air tatsu, you’ll end up in cr.mk range whether the opponent simply stood up or rolled, which you can then proceed to CADC to get back in the opponent’s face. I believe the same principle applies to Ryu, as his forward throw is the same as Ken’s.
With Heihachi, if you do his forward throw, immediately dash twice, and then neutral jump HK, if the opponent rolls the opponent will end up behind you and the jumping HK will hit them, and you can then proceed to combo them (and if they manage to block it you can maintain pressure and continue with his devastating mix-up game). If the opponent doesn’t roll, the jumping HK won’t hit but you’ll still be in range to do either + :lp: (his overhead), :f: + :mp: (his low), or :f: + :lk: (frame trap), all of which can lead into full combos on hit.
With Abel, if you connect with any version of Tornado Throw or the Change of Direction combo (ending with the overhead grab not the low), if you do LK roll as soon as possible, whether or not the opponent rolls you’ll still be in step kick range.