I have a whole lot of X23 vids on my YT (just search Merkyl999x.) I have a vid of different optimized starters, lots of match vids with ~5 different X23 teams at this point. I’m not the best match player in the world or anything, but I feel like my X23 is pretty decent.
The current optimized combo starter is the Luis Loop (s.HxxMF HxxCS LxxTA L x3, some characters only let you get 2 midscreen easily.) There’s one combo I’ve found that’s more optimized than the Luis Loop x2 midscreen but I don’t think it’s practical on stick: s.MHxxMF H, j.MH, land, instant j.M xx CS LxxTA L, land, 1x Luis Loop. I play on hitbox so the j.M xx CS L is pretty easy, but it’s not the easiest thing to do on stick.
I, personally, don’t think X23 is the best character for high level play on point (I ran her point for about a year.) She’s not terrible, she just struggles against heavy zoning and some top tier MUs so you have to be pretty reliant on your assists to do much of anything in those matchups.
As far as teams, I think Doom/Dante is a much stronger shell than either of them with Strange. I don’t know of anyone that’s done a ton of work with X23 or Dante + Rocks so you might be on your own there, but Rocks does give you an easy assist pickup after a dirt nap with JS for a guarantee so it might not be the worst thing in the world. If you run beam, you’ll have to learn the dash L pickup after a dirt nap, but you should be able to do meterless Thor kills with JS and Beam. Doom beam is pretty good for dante, also (and I know there’s a few tech vids out there for that pairing, already.)
As far as X23 assists, the LowTG is ok for dante and he can set up pressure strings that try to go into unblockables and set up unblockables after a grapple reset (nowhere close to as easily as wesker’s though. After dropping it in matches for ~2 months I finally gave up on it.) I’ve been playing Dante with CS, and I actually really like it. It lets me use EMD to get in and then set up a close range mixup with CS, it also sets up really strong mid-combo resets and gives you a legitimate incoming mixup for times when you don’t have the option to Acid Rain. Having the alpha counter option with Dante is also a huge huge thing. The one weakness Dante has is no strong defensive options and being able to turn blocking into pressure is huge.
As far as order, X23/Doom/Dante would be my choice for point X23 (easy access to Doom TAC, better damage DHC, and Doom/Dante as a shell is pretty busted.)
For bad X23 MUs, I think Dante(JS)/Doom(Beam)/X23(CS) would be better for most matchups because you get good screen coverage with both assists, you get easy access to Doom infinites, you get alpha counters into TAC infinites.