I’m just going to post about a couple characters because I won’t pretend that I’ve tried all characters with her extensively.
As a general note, Hsien-ko benefits greatly from having at least one other teammate alive when she is on point, due to assists and the DHC trick.
Doom
The majority of my time with Hsien-ko has been with Doom on the team, so he takes up most of this post.
The first is the choice of the assist. I tend to go for Hidden Missiles for a few reasons. Hsien-ko is slow and usually can’t catch up and combo from beam assist knockback. Smart use of the missiles goes a long way to help Hsien-ko’s neutral game. Hsien-ko tends to be pressed for time with the desire to keep a wall of gongs out while advancing toward the enemy, so if you get a good opportunity to put missiles out, the descending missiles can give you somewhat of a “safe” time to advance with airdash/pendulum/etc., or rebuild your position. Also, the coverage of the missiles (in the air and behind you) is an area that Hsien-ko is unable to protect on her own. That’s one big plus over a beam assist, since Hsien-ko is already fairly good at controlling the ground. In some cases it’s even safe to use missiles to anticipate someone teleporting behind you.
Missiles are also useful to Hsien-ko as a combo extender, if it’s not already been called when your combo begins. With the right timing you can call it during the ground string, do the default M M S aircombo, then one or two missiles will OTG the opponent, popping them up for another ground string into relaunch, which tends to move them quite a distance toward the corner, where Hsien-ko wants them to be. There are some other combos where you can combo into the missiles and then make use of Hsien-ko’s multiple air specials, for example if you can connect an air chain, land, and cross under with :d::h: + :a1: before launching, you knock them into the missiles and can link various things while they’re trapped.
Finally, missiles are one of the extremely rare cases that can actually allow you to combo after airthrow. Her airthrow is usually basically uncomboable, but missiles are so slow that if you called them in advance you can get a lucky OTG sometimes. And there are certain difficult setups where you can actually call missiles right before the airthrow, Hsien-ko drags the opponent down into doom’s missile launcher and you can still combo them when Hsien-ko recovers.
Otherwise, Doom’s meterless damage is somewhat of a complement to Hsien-ko’s lack of it. With Hsien-ko, you can go for an exchange and get a large air combo with Doom after the tag.
For hypers, Tenraiha can always DHC to Photon Array or Doom’s Time. From Doom, air Photon Array easily DHCs to any of Hsien-ko’s hypers, including super armor -> combo or the next character’s hyper. Other notes: you can raw tag to Doom after Chireitou and tack on an H plasma beam for extra damage. Tenraiha -> XFC -> raw tag to Doom -> stand H otg combo also works.
Others
In general I find any assist that covers a good area of the air is helpful to Hsien-ko, as is something that keeps the opponent stuck in a position for a moment or pulls them to you.
Hsien-ko doesn’t hit the scaling limit with her combos before hypers, so any kind of combo extender assist can almost double her meterless damage. It can’t be one that knocks the enemy too far away, though, like Akuma tatsu or any beam.
If the combo extender assist gives time for you to activate Rimoukon before continuing the combo, you can use exchange in combos more reliably than most characters, since the worst thing that can happen is you absorb a little damage and get a free mixup when you land.
Any character who can start the DHC trick can boost the damage of Hsien-ko’s combos. 2 characters I’ve found who suit this role are Tron and Spencer.
Tron’s Gustaff Fire assist is helpful both in its regular invincible way and also as somewhat of a combo extender. Exchanging to Tron guarantees a huge-damage combo, with Tron’s OTG ground spin -> Hsien-ko pendulum assist -> Tron capture beam xx Servbot Surprise xx Rimoukon (DHC trick damage reset) -> raw tag back to Tron -> continue combo. DHCs are fairly good between them as well, and after a Chireitou -> raw tag, tron can H drill -> lunch rush.
Spencer’s use of the DHC trick with Hsien-ko isn’t as damaging, but still useful. His slant shot assist can be particularly good for Hsien-ko, however, and he’s a bit more well-rounded than Tron on point. If you combo into slant shot against an airborne opponent, they’re placed back standing on their feet in front of you. Since Hsien-ko’s combos usually depend quite a bit on spacing, it helps a lot to be able to pull them back to you. After they’re pulled in, you can do another series for a relaunch, or take advantage of the close position and do a reset.
Usually Hsien-ko’s mixup is limited because she has a hard time catching up with tech rolls, but this way you can create a case where you know the opponent is going to be standing still right in front of you, so you can actually mix up quite well with teleport dash and high/low. It’s particularly useful when you use Slant Shot to pull the opponent back to you after Chireitou, although the timing for this requires practice.
