Hi there! I wanted to create this to show what I think the Viability Ranking would look like if it was solely based on the usefulness of a monster in the meta rather than how good a monster is in general and how useful they are. I'm only gonna show monsters that I believe would have a change in position, so if I didn't include a monster that means they would stay in the same rank. Keep in mind that this is just my opinion on this.
Warmaster Sherezar: SS+ --> SS He's a great monster overall, but this PvP meta just isn't good for him. He can't deny Area Dodge monsters which are everywhere, he can't stop monsters like Santerion or Trait Disable in general when its basically a necessity for deniers in the meta, he removes Positive effects from his team with Great Dispel which is pretty bad since positive effect status casters are great in the meta, and Great Dispel also leaves him vulnerable to popular anticipation attackers like Hookuai who can hit him since he won't be protected by Mega Taunt after using Great Dispel. He's still a great denier for the slightly lower leagues where the meta is a bit more all over the place.
Dunn Ra: SS+ --> SS- Having Mega Taunt is great and all, but having only Mega Taunt as only a status caster won't cut it for the current meta. Most meta deniers, Pumpseed, Thalassa, Grakon, etc, can easily dispatch Dunn's mega taunt with PER and deny the enemies in only 1 turn making Dunn's Mega Taunt not all that useful in this meta. PER + Denial is all too common for Dunn Ra to succeed successfully in this meta, but still serves as a menace in slightly lower leagues due to less prevalence of these kinds of monsters.
Mephisto SS+ --> S+ Same reasoning as Dunn, but is even less of an effective tank since his relics really don't help him that much and having good relics is very needed for tanks to be useful in the meta.
Makugan SS+ --> SS Makugan is a great attacker overall, but I think would drop slightly if completely based off of usefulness. As a Metal attacker she has great use seeing as many Light monsters, Wyrmlad, Nikasia, Draghar, Clipeum, etc, are very popular in the meta and she can kill them easily with her hard hitting damaging skills. She also is generally hard to deny as well due to her Trait and 0s 0 CD skill, which most meta attackers need. Sadly, she has no self support skill to help her which meta attackers basically need at this point. Her only way to deal more damage is reliant on Metal Weakness which is much worse to rely on than a positive effect.
Neobuki SS+ --> OP- Neobuki pairs extremely well with Wildbird who is a meta monster since she has many useful positive effects that Wildbird massively benefits from, especially with his trait. While this move up may seem big, she would most likely be on the lower end of usefulness in OP-. Her combo with Wildbird and Elvira is a great combo in this meta. The only reason why it probably isn't seen more is due to not many people having a fully ranked Wildbird.
Kronx SS+ --> SS Kronx has no AoE PER or Trait Disable in a meta that basically requires deniers to have both of those. She at least does have a single enemy PER + Extra turn to make use of, but sadly Santerion won't be affected by this at all. Also, with the increase in monsters being immune to control, Kronx's unique denying effects aren't as useful. She has very few ways to deny Area Dodge monsters as well making her not that safe of a choice for the current meta, but in somewhat lower leagues where these problems, like Area Dodge and Mega Taunt, aren't as common, she is a good monster.
Nitroblaster SS+ --> SS- Nitroblaster has many extra turns on his better skills, which isn't good to have when anticipation is extremely popular in the meta. Also, where Traits, like his, are crazy and require trait disabling from the enemy team most of the time, it isn't good to give them a leg up and trait disable yourself. Regardless of the positive effects it gives, it still is pretty detrimental.
O'Reilly SS+ --> SS He just gets completely outclassed in everything by Grakon. Better cursers to pick from in the meta as well as deniers. Most skills are also AoE making Area Dodge quite the problem.
Silverleaf SS+ --> SS- As a denier he has no Trait Disable, so Taunt is a problem, he has no PER either meaning Mega Taunt is a problem for him. Tanks just completely wall him in general and his other denial capabilities rely pretty heavily enough on AoE skills as well. Supporting abilities are very nice, but he can't be a full on support like more meta supports.
Warmaster Remntar SS+ --> SS As a support it is pretty essential to have a NER which sadly, Remntar doesn't have. This is the main reason I would say he isn't as useful as other supports since the meta is filled with many cursers and monsters that just apply negative effects. Having a support that can't NER your team is not good. He would be lower, but his plethora of positive effects, all being very useful in the currect meta as well, help keep him him from dropping.
Wickah SS+ --> SS- Her main use is to Trait Disable and PER the enemy team for a denier or any other monster to easily deal with the enemies. The problem is that in this current meta, you want your denier to be the one to do that, not your support, especially since Wickah can't follow up after she does Trait Disable and PER.
Cain SS --> S Anticipation literally kills his main gameplan of Bleed to enemies and do massive damage since all his bleed skills have extra turns. In a meta where anticipation is everywhere, he can't pull this combo off easily. He is forced to then run a set that relies much more heavily on raw damage making it a little hard for him to kill since he relies heavily on bleed to increase his damage output. Anticipation pretty easily stops his main gameplan causing him to not be nearly as useful.
Clipeum SS --> SS+ In a meta where Area Dodge + Taunt is one of the best combos, Clipeum definitely thrives. He serves as an amazing shield for a lot of these Area Dodge monsters seeing as he has Taunt, and his relics are amazing at keeping him alive (Nebotus' Armor and a good Shield Relic) allowing for maximum protection to his allies. Even his skills help protect them further if he manages to get a turn. He shields his allies really well, which is extremely important for a tank to do in this meta.
iMigbo SS --> SS- He's a solid attacker, but there isn't too much of a reason to use him in the meta. There is only 1 fire monster that is very popular in the current meta and there are just more useful Water attackers to choose like Hookuai and Gorg.
Koralle Brutalis SS --> SS+ Most of the same reasons as Clipeum considering he also serves almost exactly the same purpose, except he focuses a little more on the offensive side with his skills than the defensive side. His relic slots are also amazing since double shield will give him a huge shield and Pierce no longer goes through it allowing him to soak up even more damage. Additionally, Dark monsters aren't that popular alllowing for Koralle to not have to worry about a potential dark monster dealing massive damage to him.
Nabuline SS --> SS- Will explain later