Okay, now I can say I have decent experience with Ryougi. Despite what you all saw at NECX which I blame on using pad. So here's my thoughts on C-Ryougi as a whole:
5a:Horrible horrizontal range, probably your best use is as a whiff cancel.
5b/5bb:Good for catching incoming jumpers, it's also a good move for catching off of a counterhit or continuing a juggle.
5c:Good for catching but not as good as 5b/5bb. Charged version is a good choice for blockstrings
6c:A bit harder to work with than 5c but it crossups and sets up an EX. Charged version works in blockstrings.
2a:Good for poking and hitconfirming.
2b:A decent poke but not really that good, probably best used in groundstrings. 2c is a better choice for using randomly.
2c:Primary launcher, quick, long range, excellent for catching. Probably Ryougi's best normal.
j.a:Not bad but not really that useful. Could be potentially used as a jump in.
j.b:Good choice for a jump in, but if your opponent is more in front of you than below j.c is a better choice.
j.c:A good choice for jump in, covers more vertical range than j.b
214 a/b/c
a:Wallslams, if you manage to get a hit it's fairly easy to combo off of. Kind of risky since it doesn't hit most crouchers.
b:Slighly less risky than 214a since it hits crouchers but since it doesn't wallslam it's less useful. With a counterhit or aerial hit it is able to set up a reasonably easy combo. Potentially usable in blockstrings (not really the best option) or setting up an OTG (but why do that if you can combo).
c:For some reason it doens't hit crouchers. Safer to use in blockstrings than 214b/a. If you can predict a superjump whipping this out can easily catch them and set up for a combo.
In general all of them have at least minimal usage in combos but they fail heavily against antiair.
421 a/b/c
a:Basically 214b but with the slash reversed.
b:Almost exactly the same as the a version but with one key difference. You can jump out of it after the slash kind of like Akiha's air flametounges. That difference makes it much more useful in mindgames and increases the safety of the move.
c:Basically 214c with the slash reversed. Can also be jumed out of like 421 b.
Much more useful than 214 a/b/c as a whole and doesn't fail quite as badly to antiair due to the crossup. Also useful for switching sides.
Rekkas
first slash:Same for both a and b.
second slash:The 236 version grounds aerial opponents, 214 is an overhead.
Third slash:236a is a quick knockdown or juggle, 236b is a launcher, 236c seems like a launcher and does more damage than 236b but it has too much lag to be comboable out of. However, 236c does have an advantage over 236b in having more horizontal range and 236b236b236c gets you almost entirely across the screen. 214 hits low and knocks down.
EX:Fair damage, I think it has a fair amount of invincibility. It also hits within a frame or two so it's easy to get in through your opponent's EXs.
The rekkas have good blockstring potential and some combo potential if you can get the timing of the relaunch right. The EX version is a good choice for a combo ender or punisher.
623 a/b/c
a:Knockdown and a fair distance traveled. Can also be charged to turn it into an unblockable.
b:A launcher version of b, easy to combo off of if you have the spacing right. Like a it can be charged to make it unblockable but then it loses its combo potential since you can't relaunch off of the unblockable version.
c:A launcher that's very easy to combo off of if you have the spacing right.
a is more or less useless outside of it's unblockable. b and c can be used interchangeably in combos. You can release the charge early to mess up your opponent's shield or block timing. Also can be used for side switching during blockstrings since you go through your opponent whether they block or not.
22 a/b/c j.22 a/b/c
This attack is kind of strange for the ground versions. The a/b are basically the same attack but with a at a lower angle. Strangely enough both of them hit low no matter what they may look like. Both can be charged for unblockable properties. The EX wallslams and flies perfectly horizontal but doesn't hit low.
The EX is basically the same in the air but a/b change. Now they throw at about 30 degrees down. The difference between the two is that the a version flips towards your opponent and the b version flips away from them.
On the ground 22a/b are good blockstring options. 22c can be used in a blockstring but it has more combo potential due to wallslam.
When used in the air 22a/b are not really that useful, maybe as a poke. 22c can be used as a combo ender.
j.236 a/b/c
Huge hitbox with a lot of room for error. It could conceivably be used for air-to-air but it's a little slow to start up. It also has potential as an aerial jump lengthener to keep your landing time unpredictable. The a version is actually a little slower than the b or c versions and because of that it isn't as practical for aircombos.
j.44/22/66 a/b/c (instead of air teching)
At first I had no idea what this was, it would randomly pop out against the CPU and I would pull it off by accident occasionally. It's a little tricky to pull off and not exactly easy to hit with. My best thought of how to use it is anti-antiair or air-tech-punish punish.
63214 c
I think of this as an extended rekka string, My thoughts on it are more or less the same as the Rekkas. However, due to the increased number of hits it has more combo and damage potential.
Arc Drives:
Not much of a difference between the two except for damage. Both have some potential as a combo finisher. If you're close enough they are unblockable.
Last Arc:
About as useful as any last arc, but it gets bonus points for the glitch.
As you can probably guess, my way of playing Ryougi is very gimmicky. I figure that since 214 and 421 look almost exactly the same and the dash in for 623 and 421 look the same it's possible to confuse your opponent with them. Basically 6-4 mindgames into combos.
Speaking of combos, I use these:
Air combo:j.bc j.bc j.236c/b or airthrow
Combo 1:2b5bb2c5c air combo
Combo 2:2b5bb5c2c6c air combo (I'm currently inconsistent on this one, for some reason my 2c-6c connection doesn't always work)
Combo 3 (corner):2b5bb5c22c214a2c5c air combo (adding 2c before 22c is possible but I find it doesn't make much of a difference in damage)
Combo 4 (Non-Corner):2b5bb5c22c2c5c air combo