I'll be starting off on the premise that you understand the ways Iriya, Rusian, and the other assists I introduced on Twitter are used are fundamentally different from each other. Simply put you'll be fighting as Asuna while trying to protect Iriya and Rusian while the other assists are meant to supplement Asuna. In particular the first 2 are assist types that aren't seen in Aquapazza and are unique in that manner and their abilities are nothing to scoff at, the better you command them the more incredibly powerful they become.
Good at both attacking and defending, Celty is an easy to use omnipotent assist. As a side note, up until the 3rd National tournament and the 1st Toushinsai tournament, I made it to the final selections of each tourney using Celty as my main assist.
5S startup is fast and it's reach is wide, it can be used like a real projectile and is great at keeping the opponent in check
5S and 6S both have short cooldown times
She's easy to implement in combos and the damage output is fairly good
Setplay is easy to use while being exceedingly powerful (4AB can be implemented in addition to the left/right mixup and is easy to do, and seems like it'd be particularly threatening on netplay)
Against Rusian 6S or Iriya 5S after visually confirming you can easily use 5S to beat either, it's easy to function as a deterrent
During trump 6S while blocking is exceptionally superior (unlike 5S Celty herself can't get hit, so during a blockstring it forces the opponent to make an immediate decision)
Celty has a hurtbox on 5S which trades with the opponent more often than one would think. In the case of getting hit the cooldown time is long (a peculiarity of this game is that assists that are easily hittable tend to have short cooldown times when they get hit)
It's easy to beat Rusian 6S, but in the case the opponent is able to safely call him you can't really use Celty afterwards
The gap in defense and damage output when fighting someone using Iriya becomes striking. Asuna has average damage output so when facing an opponent who's finished 3 plates the amount of reads you have to make becomes increasingly high, along with a tendency for those reads to turn into bad ones.
While 5S is exceedingly potent at keeping the opponent in check, on hit you only really get a hard knockdown so at most you can OTG where the damage is pretty weak
When outside of trump state okizeme can be easily pushblocked
I came to the conclusion that against Iriya, Celty can't win so I eventually switched to Iriya. However, unless you master how to use her which can be hard within a short time span I recommend Celty. More so than Iriya, being able to easily get good damage confirms off 4AB is something highly praised on netplay. Lastly because of its straight forward nature the use case for 5S and 6S are clearly separated.
Buffing the main character+setplay are the essential factors. She's incredibly easy to hit but if you're able to protect her the grace you receive is extraordinarily high. I used Iriya as my main assist just before the 2nd Toushinsai tournament.
6S during trump is strong during neutral or on defense
One-sided setplay or offense when using plates or fireworks
In the case of using 5S during neutral and successfully protecting her, it's easy to stabilize yourself due to the high defense and offense buff
5S is incredibly easy to hit so you're required to fight while trying to protect her. Movement during neutral can feel constrained so adjusting to it is necessary
When raw 6S hits your ability to ad lib will come into question, converting into a clean combo from it can be difficult
Asuna and Iriya's potential activation requirements overlap so it's hard to take advantage of Asuna's own potential
Okizeme compared to other characters isn't as effective and it's hard to increase damage output mid combo
To be honest the synergy between Asuna and Iriya isn't that great, it's just that Iriya is so strong that you'd benefit just by using her. Approaching neutral is very different and requires adjustment, and by using her myself I get the merit of understanding what situations she can be hit etc. If you plan on using her you'll need to prepare yourself and double down otherwise it can be hard to become strong with her.
She holds 2 types of fast projectiles, one horizontal and one vertical. Regardless of the character she's paired with she's a strong and easy to pick up assist. If you're looking for high damage + keeping the opponent in check with a projectile while still being able to confirm from it into damage then you'll want to pick this assist.
6S has fast startup and in Asuna's case even if it hits at far ranges it's possible to follow up
5S is a powerful anti air that easily restrains the opponent's air movement
Both 5S and 6S can lead into good damage even from simple combos
5S during trump can be extremely effective but because you cannot hold back when using it, it can be hard to perform
She doesn't offer much in terms of setplay so it can be tough opening up opponents
One of Dokuro's strong points are her no cancel 5S combos and in Asuna's case this is hard to do
If Dokuro is hit from either 5S or 6S the cooldown time is lengthy
In place of losing the setplay you get with Celty, you gain an assist that deals high damage combos and damaging hits from Dokuro's attacks. She's bottlenecked by the lack of being able to open people up but coupled with Asuna's own abilities I'd support her from the sidelines. I recommend her for people that like to aggressively attack.
An assist specialized in setplay. She's hard to use during neutral but once 6S is activated you can one-sidedly attack the opponent. I don't have much experience with her so a lot of this is what I would imagine.
While 6S is out you can one-sidedly attack the opponent and because it's active for so long you can gain the advantage
Contrary to its appearance the guaranteed startup of 5S is surprisingly fast, because of this it can be used effectively as an anti air
The setplay options are abundant and easy to get damage from throw or left/right mixup
6S and 5S are very weak too pushblock. When you have the health advantage it can be tough taking advantage of Mashiro's attacks
Since she specializes in okizeme it can be hard doing big damage combos
Using 6S is an important element but the cooldown time is long so it's hard to use continually for okizeme
I think this assist is suited towards people who think "I want to use assists for oki!" In order to due this a lot of effort is required from the player, however because Asuna's inherent abilities are above average she can hold her own in neutral. Kasumi LOVE has mainly used this assist for a while, so if you're considering using Mashiro it might be a good idea to ask about the setplay from him lol
The assist that takes pride in overwhelming oppression. Just like Iriya, Asuna will be focusing on protecting Rusian while fighting at the same time. I don't have much experience using this assist so a lot of my thoughts will come from theory.
Once you activate 6S you can limit your opponent's movement to an astonishing amount and once he's out you can one-sidedly start to attack
5S during trump is a highly effective defensive tool
While the chances are rare you have access to a high damage double CA combo
The opponent takes white damage from blocking 6S, so just repeatedly calling and protecting him is strong
Setplay options after 6S are abundant
Getting a knockdown after 236AB creates space between you and the opponent, so protecting 6S in this case can be hard
You'll be focusing on protecting Rusian but if you can't adjust to this and don't protect him or Asuna herself gets hit before monster train comes out the move will end preemptively
Aside the double CA combo mentioned above, it's hard to increase combo damage output and the overall damage itself is on the low end
Similarly to Iriya it's hard for Asuna to receive the benefits from Rusian compared to other characters, however Rusian himself is just plain strong. It feels harder to protect him while fighting compared to Iriya, and I think it'd take some time before one could consistently win using him. I think his effectiveness will change depending on how used to the opponent is to fighting him, so in that regard he's kind of hard to recommend.
This time I'll be introducing setplay involving Asuna and Iriya. This pairing doesn't offer that strong of okizeme so it'd be wise not to hold too high expectations.
Asuna's solo setplay is mainly compromised of safe jumps.
(1) Aerial > j236B > j236AB > 5A whiff > forward jC
You can safe jump against the opponent's reversal trump card, Powerup Blast, AB, and Ranbu. If you input trump or Ranbu, in the case the opponent does Powerup Blast or trump you can automatically bait it. If your opponent has a blue trump, the player usually will be at a slight disadvantage. If you replace jC with jA you won't be at the disadvantage however, you won't be able to use the Ranbu or trump option select so be wary.
In the case of using jA: Against KYH, Tatsuya, and Shana you'll be even. While against Yuuki you'll be at the advantage and lastly against Kirito and Emi after the superflash, throw is a guaranteed punish.
If you don't go for the safe jump jC, 2 other options you can do are empty jump into throw or j236A. Throw will lose to fuzzy 5A but j236A will beat it.
In the video jC > Trump was used to bait the opponent's reversal and in the case that they block trump does not come out. When landing after jC if you don't input trump you won't be able to bait reversal Powerup Blast so take caution.
(2) Throw > OTG 2AAA > 5B > 2C (2nd hit whiffs) > 5A
Note: Yuuki and Kirito wakeup 1F slower so please use 2A against them. Shana wakes up 1F faster so this does not work against her
This is the recipe for meaty 5A from a throw. Just like (1) you can bait reversal red trump and Powerup Blast, and clash back against AB. If going for an OTG after 236AB knockdown you can use this same string, just be aware that you cannot bait Powerup Blast. Furthermore, compared to GBVS tick throws are much harder to perform. So let's make sure to use dash throw if 5A is blocked and dash 5A to beat abare.
During normal circumstances the setplay isn't that strong, just get hard knockdown from an EX move and setup Iriya. You can OTG to buy time then use 5A to launch the plate and start pressure. Because it isn't that strong the setplay will mainly come from trump state.
(1) Buttons > 236AB (delay 5S after the last hit) > OTG 2A > 5C > 5B > 2B (plate launches) > 2AA
Note: Make sure to start the OTG string with 2A hitting at the tip. If you don't do this the plate won't launch.
From this setup forward jump 2A will hit from the back, while just barely jumping over the opponent then jumping backwards will hit from the front. The strong point of this setup is regardless of what option you use the assist gauge will start to recover. After getting a hit confirm you'll be able to setup another left/right situation. Take caution however as the back option is weak to fuzzy 5A and after the fuzzy 5A it's possible for the opponent to go into ranbu or 5AB. Another point of concern is against blue trumps it will be a guaranteed punish for them. In addition, because the back option is quicker it's possible to be fuzzy guarded.
(2) Buttons > 236AB (delay 5S after the last hit) > OTG 2A > 5C > 2A
This is the recipe for when you have fireworks ready. The fireworks will be doing the left/right instead of the plate so the OTG string is kept short.
In the video you can see back, front, and back mixups. You can actually defeat the opponent with just these 3 setups lol. This doesn't apply to Asuna, but for teams who can be described as having strong left/right mixup such as Yuuki/Iriya or Tatsuya/Rusian I think you'd faint in agony.
※ Strong left/right mixups are defined as okizeme from safe jumps that can't be fuzzy guarded. For this reason DFCI is sometimes called a left/right game...
That covers everything in regards to setplay. I know it was short but Asuna/Iriya challenges your ability to ad lib more so than your chances to setup firm setplay. For example during neutral if you launch the plate with 5B into a correctly timed throw you can follow up. You'll need to get a feel for the timing of when you can follow up a combo after launching the plate. Let's try to grasp this intuition through experience.