Verse Challenge: Could the Guardian Senshi stop the Chaos Stars

The Guardian Senshi, manifestations of the 4 guardian deities and protectors of Princess Serenity

The Chaos Stars, manifestations of the primordial Chaos, dark stars sent out by Chaos to find and retrieve the ultimate power of the universe, the Silver Crystal.

At their apexes of their power, had Chaos manifestated it's aspects to kill Serenity and take her Silver Crystal and the Guardian Senshi strove to protect her, would they be able too?

This blog will take all the characters at their peaks of their personal power. The Guardian Senshi will all be in their eternal state but not their Lambda State as that's not really their personal power.

The Chaos Stars will also be at the strongest personal state, meaning Queen Metaria during the Silver Millennium, Death Phantom at the point it was going to encompass the solar system, Pharaoh 90 back when the Taioran Crystal was bright and at it's peak and Nehelenia during the modern day. There is a contention that Silver Millennium Nehelenia is stronger and while that may be true, almost nothing is known of the abilities of this form of Nehelenia and so practically speaking Mirror Nehelenia is stronger for vs debates. Humorously there is a point in each of their timelines where each of the Chaos Stars had the Silver Crystal however that is not their personal power so I won't give it to them. It also wouldn't make sense for each of them to have a Silver Crystal as two Silver Crystals existing at the same time create paradox and jam each other's power unless used by an acausal entity.

Being an intra-universal fight, this is primarily going to be focusing how strong the characters are relative to each other, rather then on their objective power relative to other verses though I will bring up mentions of that as well.

Starting with power, the Chaos Stars are all cosmic entities and almost by their nature and sheer size are designed to cause destruction on a cosmic level. Death Phantom for instance was a black hole that threatened to envelop the solar system imminently

At an earlier state of it's development, it's body was without equal of the celestial bodies

Even just using the planets of the solar system, a Black Hole the size of Jupiter would have a mass of 47,000 stellar masses. Saphir was not scared of traveling to the center of this mass where it would be concentrated

and Saphir is likely a low tier of the second arc, saying that the energy to create 2 perfect droids is "remendous"

using a Black Crystal to threaten civilian form Usagi

and calling the energy used to time travel which Droids regularly tanked to go back to the past tremendous

He also interestingly implies in the above scan that the time travel's energy is enough to cause planetary effects to Nemesis.

Peak Death Phantom obviously scales to be well above mere droids, being able to easily survive an attack from Sailor Moon after several more upgrades that sent to the edge of the solar system

The destruction of Death Phantom has been calced at anywhere from high solar system to galaxy level. Whatever level is decided for it, this level of destruction is caused by the two silver crystals of Earth and Future, one of whom he could equal with his power in his battle with Sailor Moon so he would scale to half of it.

Pharaoh 90 was strong enough to move a "very distant" galaxy close to the Earth

From that far away galaxy he was warping space all the way to the Earth

It is also stated that the Death Busters, Pharaoh 90's group of whom he is the strongest, will turn the Omega Area inot a second Tau System 

The Tau System has been shown to be a galaxy numerous times

All of this would be Pharaoh 90 when he is relatively weak, as with the decline of the Taioran Crystal, his power has declinded.

The Chaos Star Nehelenia maintained until she died the dark mirror universe, stated to be a parallel universe to the main universe and which in the artbook is stated to contain constellations

She can also seemingly manipulate the dark mirror universe which she used to show the Senshi her distant past

However none of this is at all relevant to the Eternal Guardian Senshi.

If I bring up this matchup to an SM fan who isn't into vs debating some might say "Didn't the Chaos Stars already beat the Guardian Senshi" and even the majority who recognize that the Guardian Senshi grow stronger during the series often don't understand the sheer level of power the Guardian Senshi possess in the final arc.

Upon first encountering Galaxia while both were , Usagi called her power greater then any enemy she had ever faced and by the way she states it this would be by a large margin

Which Galaxia immediatly proves by casually destroying the Holy Grail which tanked the energy used to destroy Nehelenia

Arc 5 civilian form Usagi withstood this level of energy

The Base Senshi Henshin obviously made normal schoolgirls into cosmic planetary guardians, the super henshin made Base Sailor Moon over 10,000 times stronger then the peak forms of beings that were stronger then her base form

and the Eternal Sailor Henshin is at well over 3x as it involved all the senshi using all their crystal, castle and planetary guardian's power to boost Super Sailor Moon to Eternal Sailor Moon including another Silver Crystal and the Golden Crystal which is the equal of the Silver Crystal (as well as all the other crystals, the castles and planetary guardians)

This means that Arc 5 Eternal Sailor Moon before getting boosted by the Silver Crystal would be at least 30,000x hypothetical Arc 5 Base Sailor Moon who would be some unknown but drastic amount above Arc 5 Civilian Usagi who tanked a power greater then any of the prior enemies.

How do the Eternal Guardians compare to base Eternal Moon? Whiel Eternal Jupiter was able to harma nd throw her away with one of her base, ie non galaxia-amped attacks

Animamate Tin Nyanko hurt Eternal Moon with her attack

yet the Eternal Guardians are comparable, if not outright superior to the Animamates with Jupiter tanking Iron Mouse

and Eternal Mars stalemating an attack from Sailor Lead Crow

Eternal Mars and Eternal Mercury were also pre-Galaxia amp able to one-shot the 4 Eternal Amazon Senshi

who together were strong enough to kill Animamate Heavy Metal Papillion

All of this shows that Death Phantom, Pharaoh 90 and Queen Nehelenia would have completely neglible power compared to the Eternal Guardians. That leaves Metaria.

Metaria is unique in that her full power is never fought or compared to for the Guardian Senshi. While her First Arc self when she was the size of the Earth was the weakest of the Chaos Stars

however she never regained the peak of her power obtained during the Silver Millennium where she was the size of the Sun

There's not a lot of information about peak Metaria, as SM is a very fast paced manga with 5 story arcs in 60 act and Naoko deliberately left much of the Silver Millennium in mystery to preserve it's mystique. There's 3 bits of information I use to scale Peak Metaria, 1 of which I think is pretty solid and the other 2 are a bit less so and I wouldn't use by themselves to scale Metaria, only to support the main point. The primary point is that Metaria struggled with and killed Queen Serenity though she managed to imperfectly seal it away

A lot of people take the statement of her having a weak heart to suggest that the curse Nehelenia lay on the Silver Millennium was weakening Queen Serenity's heart as it did to Mamoru, which would be relevant because the Silver Crystal's power depends on one's heart to work. 

And while I am sympathetic to this claim, and believed something akin to it for years, there are two problems with it. Firstly it not being clear that Queen Serenity is suffering from sickness. The curse of Nehelenia made Mamoru deathly ill, coughing up black blood

This happened in a span of days maybe. Nehelenia cast her curse on the Moon Kingdom at the party celebrating the birth of Princess Serenity (in an homage of Sleeping Beauty)

yet Serenity was apparently teenaged during the time of Queen Metaria's attack

Even ignoring the immortal lifespan of the inhabitants of the Silver Millennium, this means that at least the better part of two decades. Queen Serenity may have had her heart weaken from the curse, but she was not suffering from deathly illness for nearly 2 decades, not least because someone would have noticed or mentioned.

The second reason is that it honestly wouldn't matter. Being sick wouldn't decrease the durability of her skin which was tough enough to withstand the Galaxy Cauldron a force of destruction that can even destroy Sailor Crystals

and while she could not control the power of the Silver Crystal, the Silver Crystal will act to protect it's bearer without them thinking

meaning that to be able to kill her, Metaria would have had to overpower the Silver Crystal. 

This suggests that Metaria is freakishly powerful, stronger then even Galaxia who would have struggled to kill Eternal Sailor Moon via raw power because of the silver crystal's protection and used the galaxy cauldron to destroy Sailor Crystals.

There's two pieces of evidence I use to support this and they're not as concrete as I'd like and I wouldn't use them by themselves but they should be ok as support. The first is that Metaria is designated the Goddess of Darkness

Back in the early days of vs debating, saying that someone was a god or could fight gods was used as evidence they would beat any non-god and that was obviously not true but some people went too far in the other direction stating that being called a god was meaningless, when really it like any other title means whatever the verse says it does. 

Whenever a god is mentioned in SM, it is treated like a big deal. The Senshi are only the avatars of the gods

suggesting the actual Gods are stronger then the Sailor Senshi in general. Similarly Galaxia who is one of the top 10 strongest Sailor Moon characters, despite her massive arrogance never calls herself a God, only "Chosen" by God/the Gods (Japanese is ambigous with singular/plural distinction)

which may imply Galaxia views her own power as Sub-God Tier.

The aforementioned Queen Serenity is noted to be the Goddess Selene

Serenity being another one of the top 10 strongest SM characters, and makes it somewhat consistent for Metaria to be a Goddess if she can struggle with Serenity.

Again, maybe Beryl was just talking up her leader, but given that Serenity and Metaria were set up as comparable it seems like the intent was to make Metaria the goddess of darkness.

The other bit of evidence is something I've seen a lot of people misinterpret what I meant when I used it prior, which I suppose is my fault for not being clear enough. Specifically I said Metaria was implied to be a threat to creation and used this scan

Now let me clear, I didn't mean that "an enemy of all creation" meant she was auto universe level. Freeza from Dragon Ball has a somewhat similar statement iirc. 

What I was saying is that because Metaria being statement to be an enemy of all people and creation and because she was going to overrun the universe's people with the silver crystal that she would be at the very least very difficult for the people of the universe to stop. If someone was stated to be a threat to the world, what that means depends on how strong the potential defenders of the world are. The SM Universe has many Sailor Senshi and beings stronger then them like Guardian Cosmos who Queen Serenity knows about. 

Overall I think Peak Metaria's attack potency is pretty clearly vastly above even the Guardian Senshi. That said she super lacks durability feats, possibly due to lacking a physical form in the first place. She "struggled" with Queen Serenity but that might not imply she withstood a physical attack from her, as well as the fact that Queen Serenity couldn't use the power of the Silver Crystal properly and the fact that Queen Serenity's energy projection with the Silver Crystal is sub-Eternal Moon level as said by Queen Nehelenia who mistook the latter for the former

In conclusion Peak Metaria's attack potency is vastly above the Eternal Guardian's power which is vastly above the other Chaos Star's power with the Eternal Guardians's attack potency may or may not be above Peak Metaria's durability.

Moving on to speed, all the Chaos Spawns should easily be above the speed of low tiers of the verse. This includes the Stars who travel to Earth once a year every year from dozens of lightyears away

This is conservatively dozens of times the speed of light and possibly as high as thousands of times the speed of light.

Minako as of Act 1 of Codename: Sailor V before even transforming for the first time sent herself to Venus so quickly she was having trouble reacting to the events

 

Using human speaking rate got a speed of 6c with another calc using human reaction time based on Minako not registering what was happening got 12-120c 

Right after Minako faints and Artemis quickly brings Minako back to the Earth, at most in the timespan of one day

Realistically Artemis did this in seconds as fainting and remaining under for over a minute is considered highly dangerous and most faints are recovered from within seconds. This would make the speed FTL as well.

Speaking of Artemis however, both the Mautians Luna and Artemis and the Coronis-ians Phobos and Deimos came to the solar system from other star systems

As they still need to eat and drink, they would have had to travel from at least Proxima Centauri in the timespan of a few days, getting speeds several hundred times that of light. As such a minimum speed for the Chaos Stars and indeed most SM fighters is high hundreds to low thousands of times the speed of light. 

The Chaos Stars are likely signifigantly faster then this. Queen Serenity the first recieved the Silver Crystal, becoming pregnant with Princess Serenity, at the Galaxy Cauldron at the center of the galaxy

yet the party celebrating her birth was held on the moon

if Lunarian women have pregnancy cycles similar to Earth women, which is likely as they can interbreed, then she would have had to travel from the center of the galaxy to the Earth in 9 months which is 10s of thousands of times the speed of light. Peak Metaria was able to struggle with this Queen Serenity.

After the Silver Crystal left the Galaxy Cauldron, Chaos sent it's four incarnations out to retrieve it

as Nehelenia crashed the party celebrating Princess Serenity's birth, this means Nehelenia must have performed the same speed feat. 

However she is likely much faster as it is stated that Queen Serenity and Queen Nehelenia traveled from another galaxy:

As Nehelenia had at this point only existed 9 months, she would have need to travel inter-galactic distances in months at most, showing that she would be millions of times ttehe speed of light. I should note English translations differ on whether it is another galaxy or not but here is original Japanese

It's kinda ambigious here, but the picture is clearly that of Andromeda so it seems likely to me. The feat is a possible feat even if not definite.

Prince Demande of the Black Moon Clan expressed his ambition to conquer the whole of the universe

This is notable because the Black Moon Clan's rebellion against Neo-Queen Serenity was because they believed the extended lifespans granted by the Silver Crystal were heresy

To just travel the diameter of the universe once over a single human lifespan would rquire speeds hundreds of millions to single digit billions of times lightspeed and this is likely a lowball as Demande is characteristically impulsive and short-sighted, meaning he probably though he could conquer the universe and all it's planets in a short timespan. Death Phantom being Demande's superior should easily scale to this. 

Pharaoh 90 was able to move the Tau Nebula from very distant to near Earth in drastically less then a year even with the longest timespan interpretation

Moving a galaxy at visible speeds would require speeds billions to trillions of times the speed of light and it's likely Pharaoh 90 could move itself at the same time, being less massive then a galaxy. 

Death Phantom and Nehelenia both have reaction speed even higher then their movement speed being able to react to the light of the Silver Crystal

The Silver Crystal's light is fast enough to reach past the edge of spacetime near instantly

To reach the end of the universe in 1 second would be just over 1 quintillion times the speed of light, and this is past the bounds of the universe

All of this is nothing against the Eternal Guardians once again. The Eternal Guardians are stronger Eternal Guardians then the Eternal Amazon Guardians who moved relative to the lambda power, reacting and moving their hands in surprise as their stars are drawn from their chest but before it gets very far drawn to Lambda Usagi

and seeing the star seeds propeled to their proper places in the cosmos by the Lambda Power

The Silver Crystal's power is only a part of the Lambda Crystal's power meaning that the highest speed of the Chaos Stars just in the reaction speed of half of them is a fraction of the movement speed of the Eternal Guardian Senshi.

In conclusion for movement speed, the Chaos Stars are statues relative to the Eternal Guardians with Death Phantom and Nehelenia maybe being able to somewhat react to them.

All this may make this sound like a stomp for Eternal Guardians, but they truly do need this power and speed advantage. Truthfullly going into this, the Eternal Guardians were the underdogs. The Guardian Senshi have relatively unhax powersets while the Chaos Stars have some of the most broken arsenals in Sailor Moon.

Because all 8 characters have immense arsenals I am just going to over their central powersets. If you want a full guide to what these characters can do, I made a massive blog going over the capacities of all SM-verse. 

The Eternal Guardian Senshi are Sailor Senshi meaning that they possess Sailor Crystals

These emanate a metaphysical light of protection which guards them against most hax

They emanate this out as their aura of stellar energy 

These can be used for transforming into their sailor forms, blasts, barriers, and more esoteric tricks like teleportation, enchanting objects and breaking magical spells

Sailor Mercury possesses water manipulation abilities. She is also a supergenius with an IQ of over 300

and scales above Perfect Daimons with intellects hundreds of times that of humans

Sailor Mars is a Senshi with fire based abilities. She is also a shinto Miko with a mystic sixth sense that grants various types of mystic sensing

as well as is trained in exorcisms and omen/tarot reading

Sailor Jupiter primarily has lighting based abilities with also more minor affinities for wind and plant life. Beyond this she ios noted for her super strength, generally greater then even her energy projection and can effect intangible entities or other dimensional entities physically

Sailor Venus is their leader who is metal affiliated and so generally uses actual weapons as well as a more minor affinity for "Energy". Sailor Venus possesses a greater supernatural beauty/possibility social influencing

as well as some minor to moderate toonforce abilities like hearing narration boxes

talking about what events happened in the first chapter

Hurting people with her word balloon (though this may just be symbolic)

Existing and entering into a video game

Sailor Senshi have more abilities in general but these are the main abilities

In terms of Chaos Stars, they have large hax arsenals. Metaria is a non physical mass of darkness 

Her presence absorbs energy from things, turning them to stone, which at her peak she did to the moon

with the more energy she absorbs the larger she grows. She passively causes beings to go blind from her presence

and able to manipulate the minds of all humanity

Death Phantom is the disembodied consciousness, possibly spirit of the orignal criminal Phantom possessing the Black Hole Nemesis

He does all the typical Black Hole things, emanate massive radiation, absorb matter-energy to grow larger, warp spacetime dramatically, with Death Phantom in particular being able to create inter-dimensional wormholes and rip holes in spacetime with his supergravity

He has his two techniques including the infamous brainwashing Evil Eye

The Malefic Black Crystal which acts as an inverse silver crystal, distorting spacetime inwards, absorbing energy infinitely, creating cold and darkness and erasing existence

Death Phantom also is a supergenius that manipulated the populace of his world like pawns including supergenius Saphir and can see the whole spacetime continuum (though it seems that he either can not see all it's details or acausal entities mess up his sight)

Pharaoh 90 is a giant blob thing that planned to vesselize with the planet Earth (vesselization is the process by which Daimon were implanted into human bodies, using them basically as flesh suits)

Pharaoh 90 assimilates everything energy or matter used against him

While functionally Pharaoh 90's assimilation may seem similar to Metaria or Death Phantom's energy absorption, it is actually a bit different. Metaria or Death Phantom take in foreign material and convert it to more of themselves, more darkness or black hole. Assimilation involves forcibly fusing and integration the foreign material, meaning when Pharaoh 90 assimilates things he gains new properties presumably based on the capacities of what he assimilates.

As mentioned above in his power section he has incredibly storng telekinesis and space manipulation. Because this is Peak Pharaoh 90 he also has access to his daimon within him, an army of extradimensional aliens with various haxes, as well as the ability to infect people with a daimon seed by a bolt of lightning

and the Taioran Crystal at it's peak. The Taioran Crystal is actually a crystal that emanates a holy healing light

In the Third Arc it is only "dimly glowing" but at it's peak provided life for their whole Nebula

Nehelenia is probably the most complex to talk about, she was sealed away in the mirror universe behind all mirrors and can exist in multiple mirrors at once

She can project her spirit Zirconia into the main dimension though Zirconia has less abilities.

Nehelenia in general has trippy dream powers including a large number of forms of hax

She has access to two of the most broken attack techniques in Sailor Moon: Curse which changes fate to cause something to die and is not removed even if she dies

and Star Seed steal, which steals one's star seed, one's identiy a piece of one's conceptual being which causes the targeted to be erased from existence

The Chaos Stars have more abilities then these, but these are the most relevant to this fight.

In terms of weaknesses, the Eternal Guardian Senshi don't have much in the way of explicit weaknesses. In general senshi who don't possess the silver crystal have a finite energy and truthfully not all that much stamina running out of it in minutes in combat

They also possess minor psychological weaknesses but these are relatively minor and likely no more then a small advantage

The Chaos Stars on the other hand have explict psychological weaknesses

Queen Metaria has a black diamond on her forehead which is her core. A holy light aimed at her there can effect her. Holy light in general also seems to be able to effect her. 

Death Phantom is the only Chaos Star to rely on a physical body. Derived of it he is just the criminal "Phantom" who was far weaker.

Pharaoh 90's psionic throughts are so broad and strong that they can be picked up by any mild psychic in the SM Universe including all 4 Guardian Senshi

He is also the most simple-minded of the Chaos Stars.

Nehelenia is limited by the seal Queen Serenity placed on her, sealing her in the mirror. 

Meaning her ability to affect things outside her mirror universe is limited to what her spiritual projection Zirconia can do.

So Chaos re-emerges from the Cauldron as Sailor Chaos and Usagi leaves to go engage it. Sailor Chaos send it's emanations down to Earth to distract her, and the 4 Eternal Guardians leave to battle them at the edge of the solar system. What happens?

So let's start with the biggest problem for the Eternal Guardians. This was what I considered the first and biggest problem in them winning and to be honest even first going into analysis it seemed an insurmountable obstacle for them, this being of course:

THE CHAOS STARS ARE TOO BIG

The Guardian Senshi only have area of effect feats for maybe city level with Mars destroying a dimension, the Senshi's attacks being stated to destroy Tokyo if reflected, destroying the nightmare dimensions during the Dream Arc...

Nehelenia's not too much of a problem in this regard. Even at her biggest she was "only" kaiju sized which is well within city level in size. However Pharaoh 90 is planet sized, Metaria can cover the entire sun and Death Phantom can envelop the star system.

And it's not like they can just shoot them a trillion times. They don't have the stamina for that, even if they do massively outspeed. They will knock themselves unconcious just trying to blast every single city-sized area on their energy all before they can move. This means even ignoring energy/matter absorption, the Senshi would need to rely on indirect ways of winning.

On the other hand a really big boon for the Senshi is that they possess the light of stellar protection which would protect them against almost every hax that the Chaos Stars have. Sailor Moon herself has survived being within 3 different Chaos Stars and by their Eternal Forms the Guardians stellar lights are stronger then Sailor Moon in the first 3 arcs.

As they get close to them, Death Phantom and Nehelenia would be the first to react to their presence, due to their advanced reaction speed. As Senshi have on numerous ocassions sensed intent or malice

 the Eternal Guardians would probably priortize those two as targets. Nehelenia was already most likely as they would think of her as the one with the most power since she was the toughest opponent when they fought her.

Nehelenia would be a scary opponent because she may be able to cast curse through dimensions considering she was cast as she was being sealed in another dimension. If so she would have to be killed or the Eternal Guardians simply lose even if they kill her. That said they can avoid being in her dimension by Jupiter's strength. During the course of the dream arc, Jupiter from another dimension punched Nehelenia in a mirror, breaking the real Nehelenia's face

This was not just her being in vain, she thought she was about to die

Considering that another punch from Super Jupiter would have killed Nehelenia it's very likely Eternal Jupiter could quickly kill Nehelenia with a single punch. Now this doesn't neccesarily mean she can one v one Nehelenia, as in this instance Nehelenia was distracted fighting Super Moon, and so Jupiter basically got a free hit off. In this instance they would need to be able to find her, however the Guardian Senshi have the ideal way to do so, that being Ami's computer which can specifically track things in other dimensions

It's very possible Eternal Mercury could quickly scan for Nehelenia's presesnce and direct Jupiter where to punch, which she could killing Nehelenia quickly. Unless she can use curse there isn't much she can do simply due to their speed.

Meanwhile with Death Phantom, despite his speed the Senshi have an ideal counter to him, that being Rei's mystic ofuda. These banish things like evil spirits out of the things they are possessing as it did to Tiger's Eye

Despite the size, I see no reason Eternal Mars couldn't simply BFR Phantom from Nemesis, from which point it would be child's play for the Eternal Guardians to kill him. Most of their haxes would simply be resisted, things like the Evil Eye being resisted at least somewhat by Second Arc Base Senshi. The only real defense I can see him pulling is possessing Mars as he did briefly to Black Lady

However, Rei has been possessed before as SM readers may recall. In Rei and Minako's Girl School Battle, a ghost possessed Rei and it was revealed that as a symbol of their friendship, Rei actually taught Minako the Exorcism technique which Minako used to exorcise the ghost from Rei

As that is a feature of the new timeline formed from the friendship of Rei and Minako, something Death Phantom would have less understanding he probably would not be able to see this tactic coming and even if he could he would have no defense to two people vastly faster then him he can barely react to that can quickly remove him from anything he possesses, bringing out his squishy spirit.

As the Eternal Guardians regroup, if they beat those two which would be dangerous with Nehelenia but should be doable, they then would have the other two to deal with whom they have a massive speed advantage over. My guess is they would then try to attack Metaria, the most evil of the Chaos Stars, and the one they have most history with.

Metaria may seem unbeatable given her sheer power however there's a scene a lot seem to forget about from the orignal manga. All Senshi as incarnations of the Gods, like the guardian deities

 with the lights of stellar protection in them technically have a divine light within them, the shine of the stars. This can be released by the simple act of henshin and indeed in the first arc the 4 Guardian Senshi gave all their stellar energy, sacrificing their lives to awaken Sailor Moon deep within Metaria. Unlike every other time they tried to attack Metaria, Metaria doesn't laugh off their attack by saying she absorbs attacks, only calling their act of self-sacrifice a foolish display. And indeed their light does cut through Metaria reaching Usagi deep within her

This display of light was so strong that it went deep within Planet Sized Metaria. Bear in mind the Guardian Senshi at the time were much weaker then Queen Beryl and Dark Endymion whose powers come from a Metaria smaller then a room

I have no doubt that if the Guardian Senshi expelled their stellar energy near Metaria's forehead, it would kill her despite the lack of area of effect. Given their sheer power at this point and how weak she seems to be holy light attacks, they may not even need a sacrifice which is good because they would still need to fight Pharaoh 90 most likely.

However you may question whether they would know about the black diamon weakness as they were not there when Kunzite told Serenity and Endymion about it and given their personalities and how painful the fight was for Serenity, it's likely they would not have talked about it. And while this is true I don't think this would matter very much.

Not only would it likely this information have been uploaded into the Crystal Tokyo database of villains which they could quickly teleport to Earth and check, but Kunzite figured it out pretty quickly without prompting. Kunzite's not dumb or anything but the senshi have Mercury who has an intelligence hundreds of times that of a human, Venus the video game master who is used to enemies having clear weak points and Mars with a mystic sixth sense. Plus on just a basic intuitive level, it doesn't take a lot to see a giant demon of darkness whose only features include two eyes of flame, a sinister smile and some kind of pronounced black diamon on her forehead and think "hey maybe I should aim for the weakest looking spot on her body" particularly if you know you can't spam attacks very long.

This of course leaves Pharaoh 90 and truthfully....I am very not sure they could kill Pharaoh 90. They have the intel, intelligence and speed advantages clearly but Pharaoh 90 as a Chaos Star lacks the versatility of the others in exchange for focusing on one particular trait, that being his physical defense, to an excessive amount. He can assimilate all foreign matter-energy, can heal any injuiries with the Taioran Crystal, and has no clear weaknesses.

I'm go over the strategies I thought of for how they could possibly beat him and why I don't think they would work

Sailor Venus Existence Erasure Beams:

At the end of Sailor V, Venus demonstrated she could shoot beams that could erase things from existence erasure

This wouldn't work as Sailor Venus does not have the area of effect to effect a planetary sized being with these small beams

BFR:

Sailor Venus can enter video game worlds and Sailor Mercury can create hyperspace dimensions to trap enemies

However this wouldn't work as neither have shown the area of effect to trap a being as large as Pharaoh 90

The Holy Sword:

Sailor V can summon the holy sword which is highly corrosive causing the deterioration of those it touches

Possibly plausible strategy as I don't know if Pharaoh 90 interacted with the Holy Sword if 90 would assimilate the sword successfully or it would corrode him from the inside howeven given he could assimilar the Silver Crystal I don't think it would work that way. 

Barrier Containment:

The Eternal Guardians should be vastly above the Talisman Base Outer Senshi in Arc 3 who were able to create a barrier able to contain Pharaoh 90, though this would be draining to their stamina. They also use their planetary castles to erect a barrier around the star system as the Outer Senshi were going to do in Arc 5

This would be able to hold off Pharaoh 90, but it alone would not stop him....though it does lead into the strategy I think could maybe possibly work.

The Eternal Guardians retreat and create a shield around the solar system. This won't stop Pharaoh 90 indefinitely but it should cause him annoyance and anger. This plan requires one of the senshi to get and stay close as she leads him away from the solar system, however Pharaoh 90's telekinetic strength should be too strong for any of the senshi to break.....except for mighty Sailor Jupiter who is also the Soldier of Courage.

Sailor Jupiter gets close to Pharaoh 90 and bombards him with lightning and leads him away from the Solar System into that sea of stars with the other 3 Senshi monitoring from another dimension using their communicators which work through dimensions

Pharaoh 90 will likely try to trap Jupiter with his spatial manipulation, which would require coordination from 2 other senshi. Sailor Mars with her sixth sense can actually sense space beginning to warp to sense the danger in coming.

Mercury could then teleport in and bring Jupiter into a hyperspace dimension, shifting into a higher spatial dimension so Pharaoh 90's normal spatial manipulation wouldn't affect her before Jupiter returns and continues.

Pharaoh 90 may also try to send out daimon who would not be any particular threat, but as part of the plan, the Senshi could teleport one into another dimension before destroying it, let's say Mistress 9 for this example. Jupiter could hypothetically lead Pharaoh 90 to Galaxy Cauldron, the force that annihilates all stars, even Chaos Stars, at the center of the galaxy.

The goal would hypothetically trick Pharaoh 90 to go in. Given it's full of the energy of many stars, it may not be too hard if he thinks it's a source of power, but Venus could also use the disguise pen she uses to disguise herself as others to disguise herself as Mistress 9 and enter the main dimension to tell Pharaoh 90 it's an energy source.

This plan would be extreme difficulty especially since they would need to do it before running out of energy, but the basic plan of leading Pharaoh 90 into a non-physical thing that would destroy him is possible given their advantage in speed, intelligence and intel.

So overall, the Guardian Senshi stopping the Chaos Stars is technically possible, but highly unlikely mostly due to Pharoah 90.