The Amazoness Quartet are the of Queen Nehellenia, along with Zirconia. They are all young girls possessing orbs that give them eternal childhood. Their names are VesVes, CereCere, JunJun, and PallaPalla.
The Amazoness Quartet were playing in the forest when they found a dream mirror, which Queen Nehellenia spoke to them through, and began working for her when she gave them their orbs, to keep them young forever.
When it became clear the Amazon Trio could not find Pegasus, Zirconia sent them to eliminate the Amazon Trio. PallaPalla summoned a Lemure named Mr. Magic Pierrot to kill them. However, Mr. Magic Pierrot was destroyed.
From here, the Amazoness Quartet took over searching dream mirrors for Pegasus. They never had to look into them, however, as they were told that the dream mirror that contained Pegasus would be a golden mirror. They searched several dream mirrors and sent several Lemures to fight the Sailor Senshi when they tried to stop them, but all the Lemures were destroyed.
The Amazoness Quartet was always getting on Zirconia's nerves (though Nehellenia insisted she keep them around), often calling her an "old lady". They also disliked the idea of growing up, feeling it would destroy their dreams.
Eventually, the Amazon Quartet fought the Sailor Senshi, but were recalled by Zirconia and given power by Queen Nehellenia. Inside the circus tent, they gained the advantage over the Sailor Senshi, but when Sailor Chibi Moon called Pegasus, Sailor Moon defeated them. They survived, but Sailor Chibi Moon became trapped by Nehellenia shortly after, switched her around with a doll so they could ride Pegasus. They were unable to, however, and Queen Nehellenia imprisoned them inside mirrors in another dimension as punishment after finding out about the doll identity trick.
Queen Nehellenia returned them to Zirconia's room during Zirconia's fight with the Sailor Senshi, after Zirconia pleaded with Queen Nehellenia for more assistance because she was losing the battle with the Sailor Senshi team. She then decided to drain the Amazoness Quartet's power for herself to seek revenge on the Sailor Senshi team, seeing that she was losing the battle with them. The Sailor Senshi convinced the Amazoness Quartet to crush their orbs, and that this would not destroy their dreams even though it meant giving up their eternal childhood. Without their orbs, they no longer possessed Nehellenia's power, but this also meant they couldn't be controlled by Zirconia anymore as part of the Dead Moon Circus, so they were now free to roam by themselves. After realizing that they were tricked by Zirconia and were about to die, and having realized that Sailor Moon was there to help save them but didn't have enough power to defeat the now powerful Zirconia and Queen Nehellenia, they decided on a plan to help Sailor Moon. During the Sailor Senshi's fight with Queen Nehellenia, they switched the Golden Crystal (which was in her possession) with a pineapple, and gave the Golden Crystal to Sailor Moon to enhance Sailor Moon's powers.
After Queen Nehellenia decided to leave Earth and return to her own mirror, the Amazoness Quartet decided to leave quietly without a farewell to the Sailor Senshi, saying they might see the Sailor Senshi again sometime and that this is "their style" of a farewell.
In the manga, the Amazoness Quartet are present from the very beginning of the Dead Moon Circus' arrival. In the beginning, they discover that the Sailor Senshi can no longer transform and, under orders from Zirconia, they send out the Amazon Trio to attack Sailor Mars, Mercury, and Jupiter. However, during each attack, the Sailor Senshi meet other versions of themselves and gain powered up transformations. They then attack the Senshi directly when Sailor Venus approaches Dark Circus, hoping to regain her transformation as well. Sailor Venus then powers up, after learning that the Senshi powers had only been suppressed for a "growth spurt", and with the help of the other Senshi, defeat the Amazoness Quartet.
Sailor Moon confronts the Amazoness Quartet later on when going to rescue Sailor Chibi Moon and Sailor Saturn and tries to get them to not give up on their dreams, but Nehellenia attacks them before they can take her hand and traps them in crystal orbs. Later, it is discovered that they are actually the Sailor Quartet, who were sleeping in the Amazon when Nehelenia found them and brainwashed them. They were destined to become Sailor Chibi Moon's sailor team and they return to sleep in the Amazon, saying that they will reawaken when she becomes a full fledged Sailor Senshi.
Later in the middle of the Stars arc, they return and join Sailor Chibi Moon in helping Sailor Moon.
In Sera Myu, the Amazoness Quartet first appeared in the third stage during Kessen / Transylvania no Mori (Kaiteiban) - Saikyou no Kataki Dark Cain no Nazo, where they also known as the Samael Quartet and had a different back story. They were Homunculi that were growing in Samael Flasks in Professor Tomoe's laboratory. They needed a pure heart to be given a soul and the Quartet had been created with Chibiusa's starseed. Since she was rescued their connection to her was limited and before they finished growing, Chibiusa's starseed was removed. However, they did have mysterious dreams and visions of one another. The Quartet were at times under the control of mysterious Lilith_of_Darkness. With the friendship of Mandrake and because they were unconsciously devoted to Chibiusa, the spell was broken and they became the Sailor Quartet to help Sailor Moon in her fight.
- The Amazoness Quartet, as well as the next group of villains the Sailor Animamates, are the only villains known to be Sailor Senshi in some version of Sailor Moon.
- The Amazoness Quartet were the only sub-villain group in the manga that were never destroyed, rather they were healed by Sailor Moon and returned to their true forms as the Sailor Senshi of Sailor Chibi Moon.
- In fact, they are the only sub-villain group to be redeemed in both the anime and manga, albeit under different circumstances.
- Their group name is likely derived from the mineral Amazonite, which is sometimes called Amazon stone.