Ky vs. Sol
I think this matchup is dead even, and pretty typical as far as Ky matches go strategy wise. Ky will try to hold back the tide with his superior spacing and ground pokes. Sol will try to establish katame, and end the round with one momentum run.
For those unfamiliar with katame, it's a situation where because you blocked something, the opponent gets a chance to end the round or gain a heavy advantage only because you blocked. Even though blocking is the incorrect move in a katame situation, it does occur rather often in matches. The most famous example is Eddie making you block something, which allows him to use a little Eddie to chain off the blockstun and possibly ruin you and end the round.
Although other ways of dealing with Sol also work (Mitsutoshi's wall-like Ky comes to mind), I personally play in faith's "negative-style" Ky. Faith was known not really for doing fancy things on offense or defense, but rather for an active neutral game using spacing and pokes to bait the opponent into doing something that would otherwise be normal for the character, but gets counterpunched by a perfectly positioned Ky. If you do this right, then your opponent will feel like he has no idea what to do anymore, as all of his normal offense gets completely cut off. I highly recommend watching any old footage of Faith to get an idea of how this works.
Defense
Keeping in line with Faith's negative style of Ky, you shouldn't really do anything fancy on defense since Sol can ruin you very quickly off of one hit into the sidewinder loop. Rather you should be looking for ways to honestly end his offense quickly. 1F jump/super jump into airdash, dead angle, 2P, creating space from FDing to escape, and other safe options should be your primary means of defense. VT is not really good since Sol's 2D will go under it, leaving you vulnerable to a sidewinder loop. Strangely, 5k will also kick Sol out from doing 2D or brashly running in, and you can autolink that into 5HS, but you have to be rather careful with sticking out 5k willy-nilly.
Sol should not be coming at you from the air unless he has forced you to block a FRC gunflame. 6P, 2HS and SVT will ruin pretty much all of Sol's air pokes. Non-FRC Bandit Bringer without the FRC gunflame is a mistake almost everytime and you should make him pay for it with a SVT just before it hits you, to counterhit Sol into the air. Non-FRC gunflame is also punishable by greed sever or IAD S, but you should wait and pause to confirm that there's no FRC before committing to it.
FRC Gunflame allows Sol to establish katame, and you should avoid blocking the gunflame if you can, although it is easier said than done. I try to backdash or IAD backdash away or if I'm in the corner, try to one frame jump out. Good sol players will do a block string off of a somewhat far poke into FRC gunflame to establish katame. From there, he has many options which could cause you to lose very quickly. He can do jump slash, jump attack feint land 2D into bandit revolver, jump attack feint airdash S D, etc.
Even if you defend correctly, you are still in block stun so he can then run in with either 5K (to ruin backdash and one frame jump), RC VV (to ruin any 2P or other poke attempts), or wild throw (to ruin blocking). Guessing right here just allows him to do a block string and possibly build enough meter to initiate another FRC Gunflame, so this is a very bad situation that should be avoided. If he hits you off of anything at either juncture, he can send you into a sidewinder loop, and you'll lose the majority of your life.
25% of this matchup depends on how effectively Sol can establish katame versus how quickly Ky can avoid or break katame. As Ky, you should try to learn to avoid or break this situation as it occurs.
Offense
I tend to keep offense simple against Sol. Rather than do anything special, I try to do various safe blockstrings and staggered pressure to try to get Sol to hang himself either with a desperate VV or grand viper or whatever.
2K, 2P, 5P, 2S, 5S, are all pretty effective against Sol for pressure. If you pressure him enough you can do some other irritating things like FD brake throw, or FD forward slide throw (I'll explain in the FD Shenanigans section) to get him to do something. Keep in mind that Sol can VV out of some pokes pretty much on reaction (6H, 6K) and he can also grand viper under SEs and CSEs so those should be used rather sparingly. If you block a grand viper, you can actually throw Sol out before the last hit connects, in case if your opponent likes to RC on the last possible hit. That may work for a surprise or two.
He can also grand viper or VV out on reaction to an okizeme CSE or air CSE, so you have to be a little careful with respect to how you use them. In this case, I think the FB CSE works surprisingly well on oki, as well as safe jump S, star oki, Ain's Prison, and safe air backdash S mixup.
If you do manage to get a CSE out before he can do a reversal, sometimes a forward sliding FD will bait Sol into doing something stupid.
Ky's offense really only wins this matchup 25% of the time, as most of the time you are simply trying to goad him into hanging himself.
You should also learn the Sol specific punish combos, as he is kinda weird. For example, VV lands as crouching, so 5S into 6K -> HSE is one combo to practice.
Neutral
I think 50% of this match is decided in the neutral game. It will really be a battle of holding back the tide versus the tide breaking through. The better footsie player in this situation will tend to win the match.
Both Sol and Ky will mostly be deciding this on the ground, as neither can really jump in on the other due to their effective AAs. Sol's 5K and VV pretty much beat all of Ky's air pokes, whereas Ky's AAs will beat pretty much all of Sol's air pokes. Sol is slightly better air to air with his 6p, but this situation should not really occur that often. Sol's effective options are far S, 6H, 2D, 6P, gun flame, VV and grand viper. Ky's effective options are 5S, 2S, 5H, 5k, very occasionally SE or 2H, and 6P.
Keeping with faith's negative style, you will mostly be playing an active neutral game not to establish your own offense, but to cut most of Sol's offense off. You should keep yourself just about 5S distance away and stay lock step with Sol to cut off his options. Ky's ground pokes are superior so primarily, you will be deciding the battle by effective spacing and counter punching his attempts to do something on reaction because of your spacing.
From this distance you can react to a lot and goad Sol into doing something. For example, feinting a 5S -> SE string with 5S -> 2S instead can sometimes bait Sol into doing a grand viper, so keep that as an option. If Sol screws up a FRC gun flame, this is the perfect distance to react and punish with an IAD S. If Sol tries to super jump over you, well, that sends him into the air, which isn't a place he wants to be against Ky.
5S and 2S check Sol from running into you, and occasionally, stun dipper will as well, so you should use as needed. If Sol does an IAD, either 6P, 2H or 5H can counterhit him into sadness. If Sol starts randomly VVing from that distance, then you've pretty much mind screwed him over.
Good Sol players will try to patiently push in with far S, 6P, 2D or gun flame. Sol's far S and 6P will beat out Ky's 5S, so you may have to switch to 2S or intermittent SE. That's where the guessing game really begins, but Ky has an advantage in that his pokes will tend to win out.
Sol has some ghetto tricks like random grand viper or riot stop FRC into grand viper. For Riot Stomp, the FRC point is pretty close to where he leaves the wall, so you can pretty much wait until it's on top of you and then 6P. Same with the Bandit Bringer and Bandit Revolver, you can 6P or SVT CH out. As for random grand viper, again, the guessing game really is to dash brake versus 5S versus 2S versus an occasional stun dipper, but the risk versus reward is not really in Sol's favor.
Overall, the match is even. As long as you can use your superior ground game and effectively space yourself to cut off Sol's options on reaction, then you will definitely have at least even chances to win. However, if Sol does manage to get katame, he gets his chances to end the round very quickly.
I think this match vid of mine (@ 3:24:15) gives a good idea how simple offense and an active neutral game in a negative style can seal out Sol. Luckily, Spirit Juice doesn't really play and isn't very good at establishing katame, as my defense was pretty godawful here....
Next up:
(requests)
FD Shenanigans
Defensive Tactics with Ky (maybe)
Effective use of the Stun Dipper
Optimizing Damage in Endgame
Effective use of the Greed Sever
Ky vs. May
Ohoho, we're finally going to have a real Anji, instead of our fake pad Anjis :o Guess I'm going to have to show up to dogfight this week. Welcome to Nor-Cal, though you may find our level of play in GG to be somewhat disappointing as of late (´･ω･`)