alright, my bad for the late response
so, starting out, obviously mash has a massive stat advantage here. he's roughly 3x stronger AP wise, and he's ludicrously stronger in LS. suffice to say, if he manages to get in close on shunguang, it's not going to be good for her at all. she might be able to close that AP gap with her various ways of boosting her damage, and she has ways of negating mash's resistance/durability, but the LS gap is something she can't really contend with, and given that mash seems to be very prone to going for things like restraining/chokeholds, i think if mash manages to get his hands on her she's kind of cooked
considering the starting distance, and the stage itself, this does actually give shunguang a pretty good advantage in the early game. the wide expansive area lets her float up and start her danmaku spam immediately, which means mash is gonna be forced to go straight to her. now, from the examples listed above, mash does seem to at least have experience against danmaku users, so the massive rain of swords aren't going to be something that catch him off guard, but...
Yeah, Shunguang's deal isn't really new to Mash, in fact he's toyed with those who've summoned swords before, usually using them to brush up on his bunting skills.
That's not all, but he's also dealt with those who specialize in danmaku involving sharp projectiles, simply calling Cell War's carbo-rain "played out" and easily avoiding them. When it comes to an advanced level of this kind of magic? He avoids each and every one of his blades, before running around the area at top speeds to trick him into thinking he was running away. Evidently this was not the case, only a ploy to get behind and put him into one of his signature Muscle Magic skills: Biceps Magic - Python Choke
gonna be honest, i think these examples of sword summoning/danmaku really pale in comparison to what shunguang dishes out. i mentioned this in the isamu debate, but again, shunguang's danmaku isn't just a light rain of a couple dozen or even a few hundred swords,
it's quite literally thousands. and considering the openness of the stage, it means mash kinda has no real choice but to face them directly head on.
i don't think the danmaku would slow him down entirely, but i do think it makes it harder for him to close the distance between himself and shunguang, though not impossible. his AP advantage means he'd likely be able to just deflect a lot of the swords being thrown at him, and even if he gets hit by a few, he should be tanky enough to just fight through them even if he gets turned into a pincushion.
mash obviously has ways of closing the distance between him and shunguang, but i think she still has ways of defending herself in the event mash gets close enough to her, namely her IA and vital view.
vital view is kind of going to be carrying shunguang here, since it gives her ample time to react to mash's advances to either make more space between them or to counterattack.
speaking of counterattack, the big elephant in the room here is shunguang's spatial attacks, which should be able to just one shot mash if she manages to land them. obviously, way easier said than done, since mash has IA + enhanced senses that basically let him immediately sense a dangerous attack before it lands, but her charging up a spatial attack would be a good way to force him away, especially if he's in danger of getting close. though, i think there are two scenarios in which shunguang could land a spatial attack. the first is if it's chained with vital view, in which case the ridiculous perception amp i think just gives shunguang more than enough time to fire one off before mash can react, and the second is if she decides to just go hail mary and
nuke the surrounding area in a massive AOE.
like i mentioned earlier, i do think if mash manages to get even a good hit on shunguang it's basically GGs, but i think she has ways to both spam her danmaku from a distance and keep her distance to slowly chip away at mash. the longer the fight goes on, the more shunguang's damage is going to ramp up, giving her the opportunity to close the AP gap and make her attacks actually dangerous, which would be pretty bad for mash. and there's still also the danger of her OHKOing him with a spatial cut, which i do think she could pull off with vital view or just by dropping the aforementioned massive AOE nuke
definitely don't think it'd be easy for her by any means, but i do think she could squeeze out a W here even with the stat disadvantage