Bit late, but regarding O.Chun:
VF4, you’re right about keeping her as a back-up in tournaments where only one version of a character is allowed per team. I keep in practice with her in HSFII and ST since they still have local arcade tournaments not far from where I live. Here’s everything I’ve managed to learn about her playstyle versus that of N.Chun:
-Reversal SBK is easy to safe-jump (13 frames startup), but has an extra hit that knocks down (frames 14-17), often crosses up the landing hit, and recovers quickly enough to let her be safe (especially short, but all versions are 6 frames faster on recovery than the N.Chun versions). No invulnerable hitboxes, but the decent damage and knockdown often result in favorable trades. Of course, she does not possess the upkicks of N.Chun, and SBKs are performed with a down to up charge instead of away to toward.
-Her poke rush is hindered by the fact that her standing strong hits so high, since opponents can crouch under it (and st.lk). Unless she’s close or crouching, all of her pokes hit close to head-level.
-She can cancel her far standing fierce into a special move, which makes for a few good situations to push back or catch your opponent off-guard.
-O.Chun’s jumping forwards (both diagonal and neutral) have insane priority, as no vulnerable (blue) hitboxes extend out from her body at all. Neutral jumping forward also stays out for 6 frames longer (60% longer than N.Chun’s). Diagonal jumping short and forward have a higher hitbox at her head, though.
-Diagonal jumping roundhouse hits lower, making it slightly harder to combo with late, while neutral jumping roundhouse has her leg hitbox pulled back behind her at first (similar to the startup of her command forward flip kick).
-Some of O.Chun’s close normals are slightly slower, though this is hardly noticeable in practical play.
-The head stomp is easier to pull off, as all three down directions and forward execute the move in the air (instead of just straight down like N.Chun).
-Her knee bash can only be done up close, so it’s less useful for evading fireballs or beating limbs. Her trajectory is the same as that of N.Chun.
-Flip kick is much more interesting with O.Chun. It can only be done up close as a command normal, but it starts up a little faster, combos for two hits, can be cancelled after the first hit, and has an extra four frames (versus N.Chun’s) where she has a great anti-air hitbox that knocks down for really good damage. Colorful side note: N.Chun’s flip kick doesn’t combo the two hits, but both are still present, and the second hit does knock down (during frames 13-16).
-O.Chun’s lightning legs all have similar recoveries; they are not dependent on the strength of the kick pressed. According to frame data online, they don’t alternate between hitting and non-hitting frames like N.Chun’s do, but I haven’t noticed a real difference in any practical applications.
-O.Chun is particularly good in Hyper SFII, where her already great throws are untechable (along with having no super and being herself unable to tech throws).
-Turquoise is an awesome alternate color.
That’s my list so far; hope this helps anyone curious about giving her a shot. I actually prefer her over N.Chun versus Zangief in particular, but your mileage may vary.
Also, THANK YOU to those of you posting these vids; they’re a great learning tool, and highly entertaining.