I’ll share my thoughts on some mathups.
Yun
He isn’t that bad really. stHP stuffs his dive kick, which also loses to EX NDL and a well timed crMP or AXE. If he backs off to build meter you can chase him with EX NDL and regular NDL until he starts jumping, only to be caught by an EX DRA. He can’t fight as well as you in the air and surprisingly doesn’t have that many options when it comes to anti airs. Twelve can run away from Genei Jin all day and night long but a good Yun doesn’t activate it randomly from mid screen distance. If you can keep away from a Genei Jin, the match is close to even. 3-7, almost a 4-6 in my opinion.
Ken
Ugh…just ugh. And argh too. Well the strategy I follow to lose less miserably is to wait a little and see what the Ken likes to do and counter accordingly. I try to bait every Shoryuken I can and punish with anything, from XNDL to a jab, to make him think that his Shoryuken isn’t safe. This alone makes the match much more manageable. As long as it works at least. Other thing that sometimes work is to neutral jump in his face when he is knocked down. A lot of people go fo EX Shoryuken here, which is only a one hit parry on the apex of your jump and you recover earlier than Ken. Always keep my distance and build meter when it is safe, Ken cannot hurt me when he is far away but I can NDL him. When the chance presents itself I turn invisible. Almost everyone I’ve played go for a jumping EX Tatsumaki or something or spam Shoryukens like crazy. Both are easy to deal with when he doesn’t know where you are. Rare people stay on their toes, usually resulting in mere block damage from NDL or AXE but hell the simple fact that you made Ken stop rushing you is good. Also, I burn every single EX I can because oportunities to land a super are so scarce. Shotos’ crMK and crHK for some stupid reason beat Twelve’s crLK clean. Shotos’ sweep can be punished if blocked with crMK if he didn’t do it from max distance. stLK beats his ground Tatsumaki if done right but why would he use it? After all is said and done, Ken is madly difficult to beat. 2-8.
Dudley
I find this match to be very fair. I mean, Dudley is ways ahead of Twelve but what works here works just as well against everyone else. He doesn’t have an evil built-in anti Twelve engine like Ken or Urien. Dudley is one of the easiest characters to land an anti air XNDL on because of his jump arc and also to parry bait with jab. I always keep my distance since he is so dangerous up close and I don’t get very close when he’s cornered either to prevent a throw from ruining my round. I keep my cool and wait for him to do something stupid like a random uppercut, Machine Gun Blow or Ducking whatever. In case that scares them I change to offensive. If he corners you, you better block right or wake up XNDL praying that he messed up the timing on his crHK. 3-7.
Yang
What works for Yun works here too but for me Yang is harder. This is because, contrary to Yun’s lunge punch and roll, his mantis slashes are safe when blocked and impossible to block on reaction if EXed. If he caughts you in two or three loops you are most likely stunned and soon killed. 3-7.
Urien
Dear lord is Urien favored in this match. No need to go in detais, you know he is nuts. What I do is to poke him a lot with my normals when close and with NDL when he is far. Normally, Urien players will do a tackle or dash blindingly to close the distance between the two of you. That is when I put a NDL in between us to catch him in the middle of the tackle/dash. This puts them off and they start to jump, setting themselves up for XNDL, EX NDL, EX DRA, etc. Things to remember are that stLP, crLK and far stMP stuff his headbutt, he can’t do anything to instant air AXE and wake up AXE save parrying (MAYBE an EX tackle in the wake up case) and that it is possible to block a tackle super canceled in an Aegis Reflecor and reversal XNDL before the mirror can hit you (and almost certainly hitting Urien in the process) because the super makes you invincible for long enough. You still take damage from the mirror but it is better than dealing with Urien’s mixup. 3-7.
Oro
Oro is hard. Very hard. For starters, his stHK beats everything you have. EVERYTHING. Literally. You can’t approach him by the land. He can Sun Disk, Oniyama, activate SA3 or parry and launch you when you are in the air. If you haven’t noticed yet, this is one of Twelve’s toughest matchups. When he is far and throwing Sun Disks carelessly I poke him with NDL. You have to try and fire the NDL at about the same time Oro releases his projectile or it will hit you anyway. This is bad - the trade is in his favor. If he continues with this nonense build metter and parry the Disks until you score an EX NDL knockdown. He will most likely approach you via jumps and here things get ugly again: his double jump messes up royally the timing of stHP and NDLs, all while he is generally too high to be caught by DRAs. From there he may proceed to pressure you with stMP and stHK, against which you can do nothing besides block, parry or psychic XNDL. I can’t stress enough how bad Oro’s standing HK shuts you down in this match, it beats all forms of IAD, AXE and all your pokes clean. When he gets tired of it he can simply DASH UNDER YOUR IAD and launch you and blagh blagh blagh. So, what to do? Everytime he jumps I look for a double jump and dash or walk under him to make him sad. When he is close I block low like no tomorrow and wait for him to mess up or lose patience and dash or jump towards me. If he decides to stay away I continue with my NDL spam and throw a stHK here and there to catch him early jump or whatever. It is safe if parryed from full distance, he isn’t fast enough to dash up to you in time. Other thing that really screws you is his Oniyama (dragon punch), it beats AXE on the wake up, he takes like 10 steps foward in the EX version and, you will love this one, its ground recovery makes Oro duck, avoiding your clMP. That is bull. One last note, if you block a chicken you have time to walk up to him and clMP xx SA1. 3-7.
Alex
For some reason I have a lot of trouble against Alex no matter what character I am playing so take this paragraph with a grain of salt. My approach depends on his SA choice. When he plays SA2 I know he has an usable wake-up move and is much more likely to ram me with EX Elbow Rush and EX Stomp. I don’t even try to parry his moves in fear of eating a hit confirm. I don’t pressure him that much when he is down because he does not mind burning that extra EX. In case he sticks with SA3, I throw a few more random crMK and LP or MP NDL from mid and far range to catch him in the middle of his Elbow Rush. I also pressure him a little more when he is knocked down since he probably won’t waste EX and throw away his super because of Twelve, unless he is about to die. Some people do wake-up/random SA3 which is really annoying 
I don’t remember exatcly what move Twelve can use to beat the Stungun trap but I think it is light AXE. 3-7.
Ryu
While not as bad as Ken, he can beat you even faster than him if you fall for his mixup more than uhh once I think. The thing with Ryu is that when you mess up, he makes you pay for it. I try to be even more safe in this matchup than usual because of that. Fewer parry guess, fewer IAD from full screen for no reason, fewer meaties. To get near him I simply walk so I can block/walk under a random EX Hadouken, Joudan, Tatsumaki Senpuu Kyaku or jumping Tatsumaki. If you let Ryu stay close too you for too long you will inevitably eat damage sooner or later, keep him off at any cost. Then I go for a standard fare of poking with NDL and catching his jumps early with stHP or stMP. Don’t spam them because Tatsumaki beats them clean. Crouching MK is safe from a distance, it makes you low enough to avoid a Tatsumaki, just don’t spam it either because if he parries or counters it with his own medium sweep you are dead. When he jumps into you remember that his jHK at worst trades with AXE. Shotos’ crMK and crHK for some stupid reason beat Twelve’s crLK clean. Tatsumaki beats stLP and stMP. Air Tatsumaki beats all your jumping attacks that are not way higher or lower than Ryu, such as jHK hitting his head and jMP hitting his crotch, respectively. The latter is harder to do but who cares, why the hell are you jumping on Ryu anyways? When he doesn’t Tatsumaki he can jMP which really screws you so don’t jump that often. EX NDL makes you duck low enough to avoid a Shinkuu Hadouken but heh don’t count on it. Regular NDL does the same but it is insanely harder to time. Shotos’ sweep can be punished if blocked with crMK if he didn’t do it from max distance. XNDL’s startup makes Shinkuu and Denjin Hadouken miss, you gotta remember this. Twelve can walk under his ground Tatsumaki and fireball. 3-7.
Elena
My experience against a good Elena or any Elena for that matter is lacking so all I can surely say is that yes her back HK beats everything, every god forsaken sprite of hers look the same, her poking game is light years ahead of yours and her throw seems to have no startup, no recovery and to be untechable. 3-7 probably.
What I like to do in general is to IAD and regular air dash HK/HP cancel randomly back and forth. This usually makes them impatient, wich leads to dumb things like jumping from full screen. Air dashing against the wall behind you works wonders too, a massive amount of people try to chase you with a jump, only to be met by a medium punch in the face. I whore jump back HP a lot, it is such a good general purpose move. Except for that time a Ken beat it wih LP, that sucked When I am knocked down I back dash 99% of the time if I am not cornered and even sometimes when I am cornered. There are not much things in the game that can catch you in the open when you back dash. When I do it in teh corner is to gamble a hit confirmable move reseting me and breaking my oponent’s confirm, but it depends on the match. For example, Chun Li’s SA2 does not caught you if you are reset, Ken’s does. I throw an UOH every now and then; they have no real incentive to not block or parry low from mid to close distance so I think it is important to keep them guessing and sometimes connect a SA1 for free. Walking foward under their pokes and jumps is guaranteed fun. Empty IAD or regular air dash to bait a parry or throw whiff works from time to time but you gotta have balls of steel to do that.
I will continue to edit this post later.
