Movement and Neutral Options
X-23 has excellent movement when close to the ground with a very fast grounded dash as well as a powerful walljump and handful of mobility-enabling special moves. Walljump, j.2H, j.623X and j.236X all give X-23 possible ways to alter her jump trajectory, giving her ways to maneuver around an opponent's long-range attacks and close the distance.
Besides her solid ground dash, X-23's main way to force her way into close range is to make use of Talon Attack (j.236X). Specifically, doing a TK M Talon Attack j.2369M very low to the ground will connect with standing opponents (regular sized characters can duck under it) and can be supported by typical horizontal coverage assists. Alternatively, X-23 can jump/superjump and use j.236L as a pseudo-divekick to force her way in. Neither of these options are unpunishable, and both of them will lose to an opponent who knows to chicken guard them. Chicken Block -> Pushblock -> Airthrow will punish j.2369M at most spacings, and Chicken Block -> land -> ground throw will punish j.236L. However, this can be difficult for the opponent to reliably pull off in-match, and Talon Attack is otherwise fairly safe, even being advantageous on block if spaced well.
Mixup Theory
Unfortunately, almost all of X-23's mixup options outside of Dirt Nap Unblockables are susceptible to being up-backed out of, and X-23 has limited options to meaningfully punish opponents who higher up in the air.
Fuzzy Guard Instant Overhead
X-23's j.M is a fast, downward-angled attack. Unlike many other characters, X-23 can convert a j.M done on the way up by doing j.M j.2H > j.236L. X-23's j.M does not reach low enough to naturally instant overhead most characters, but it does connect on the following larger characters while they are crouching:
Sentinel, Nemesis, Hulk, MODOK (This list may not be comprehensive)
Against normal-sized characters, X-23 can still perform an Instant Overhead j.M by setting up Fuzzy Guard. The main way to do this is by utilizing a 214H command jump to attack with a j.H or j.S low to the ground, then land-cancel the recovery and rejump with j.M. The sequence would look like this: 5H > 214H, (delay) j.S land, (dash) jump j.M j.2H > j.236L, 5M etc.
Even if the opponent push-blocks the "jump-in" j.H/j.S, they will be stuck in Fuzzy Guard long enough for X-23 to dash back into range regardless. As a result, dashing up to either OH j.M or Low 2M is a real mixup once the opponent has committed to stand-blocking the jump-in attack, which is probably X-23's most reliable way to open people up.
As with most other offense, this becomes much more effective when supported by assist coverage, since otherwise opponents do not have much reason to let X-23 set up a 214H without either jumping out or pushblocking the prior hit.
Mirage Feint Crossups
214M has passthrough, allowing it to cross-up opponents, and can even steal the corner. X-23's air normals do not have particularly deep cross-up hitboxes, so this is her only real Left/Right mixup potential.
For a solo mixup, X-23's main option is to cancel 214M into L Talon Attack. The input looks like 214M214L, because the side-switch from Mirage Feint will cause the 214L input to instead come out as j.236L. However, attempting this type of setup solo is very dangerous, as it loses to a variety of options. If the opponent pushblocks the attack which was canceled into 214M, it removes the potential for Talon Attack to hit cross-up. In the worst case scenario, it can even cause Talon Attack to whiff and become punishable. Also, 5H > 214M > j.236L has a very large gap, which means it can be interrupted by any number of decent abare normals, as well as dashed or jumped out of.
It's safer and more effective to use an assist as the cross-up hit. A sequence like 5M + Assist > 214M can be timed very ambiguously to make the assist hit either before or aster the cross-up. It still loses to pushblocking the normal attack, which removes the crossup possibility, but it protects X-23 from being outright punished on a failed cross-up attempt.
Unblockables
The most effective offensive tool, X-23 has is to simply activate her Silent Kill (214XX) Level 3 hyper, then attack with unblockable S buttons. This is especially effective as an Oncoming Mixup, and can be completely inescapable if done correctly. Silent Kill's unblockable is not a grab, so an oncoming opponent has no protection against it, and it can be performed to an opponent stuck in blockstun.
If you have an assist which can hit meaty at Oncoming Height, a Silent Kill unblockable is as simple as activating the hyper while calling the assist, then jumping at the opponent and mashing S. An unblockable hit against an Oncoming opponent in the corner leaves them open to being juggled afterwards without needing an OTG, which can be seen in X-23's Combo Page. If the assist is truly meaty, this can only be escaped by characters who have a frame1 invuln air-OK hyper, which is essentially only Sentinel (Phoenix also has one but X-23 does not have to commit to attacking until she sees that Phoenix is trapped in blockstun, and can punish a whiffed Phoenix Rage.
Without an applicable assist, X-23 can still perform a solo meaty on an oncoming oppoent into an unblockable. There are 3 basic ways to do this:
- Stand under the oncoming opponent and use 623H > S
- Neutral jump into j.236M > S
- Superjump above the opponent and divekick into them with j.236L > S.
They all share the same weakness that a well-timed X-Factor Guard Cancel on the meaty hit can let the opponent escape by airthrowing X-23, and also mashing airthrow even without X-Factor may let the opponent grab X-23 if her attack is not timed perfectly.
Counterplay
Broadly, X-23 struggles to fight airborne opponents, especially at superjump height, and can be consistently countered as a point character by anyone who is capable of fighting effectively from the air. She has very poor airthrow conversions, being unable to convert from her back-airthrow and having limited follow-up potential to her forward-airthrow. Her ability to confirm a hit at superjump height is also very inconsistent.
Similarly, almost all of X-23's potential pressure and offense outside of unblockable setups loses to Chicken Blocking. Her j.236L, which is normally a safe and strong approach tool, is punishable when airblocked low to the ground. j.236M can also be punsihed if you intentionally up-back into it, then pushblock to remain airborne and airthrow the recovery. All three of X-23's 236X specials can be beat by holding up-back, and so an opponent can always react to the backflip animation of any of these specials to jump away and escape pressure - effectively rendering her command grab useless except as a knowledge check.
Pushblocking X-23's normals will shut down her ability to cross-up with 214M or to set up Fuzzy Guard High/Low with 214H. Staggered L normals can bait pushblock, but you can use a Defensive Pope Select [1], 7H~LM to consistently escape any gaps in her pressure with either an up-back or throw.
