Ramayana mentions Mata Parvati(Uma) as consort of Mahadeva.
"On going to the northern side of Himalayan Mountains, that God of Gods, Shiva settled down in ascesis along with his consort Uma on the peak of a mountain emerged from Himalayas.
Source : Valmiki Ramayana Bala Kanda Sarga 36
"What was predicted by Parvati the consort of Shiva, Nandishvara the attendant of Shiva, Rambha the wife of Nalakubara and Punjikasthala the daughter of Varunda has come to pass! The words of the sages never prove false."
Source : Valmiki Ramayana Yuddha Kanda Sarga 60
Mahabharata too mentions the same.
Hearing these words of those munis with souls under perfect control, the lord of all creatures--the husband of Uma said, 'It behoveth you not to indulge in any grief on account of Phalguna! Return ye all cheerfully and with alacrity to the places whence ye have come. I know the desire that is in Arjuna's heart. His wish is not for heaven, nor for prosperity, nor for long life. And I will accomplish, even, this day, all that is desired by him.'"
Source : KMG Mahabharata Vana Parva Kairata Parva Section XXXVIII
She is divine. She is the Supreme mother of the Universe. She is Yogmaya, the sister of Narayana, she is the one who rescues devotees from her difficulty. She is the eternal bestower of boons. She is the one who terrified Kansa. She is the giver of prosperity and destroyer of asuras.
Vaisampayana said, "And while Yudhishthira was on his way to the delightful city of Virata, he began to praise mentally the Divine Durga, the Supreme Goddess of the Universe, born on the womb of Yasoda, and fond of the boons bestowed on her by Narayana, sprung from the race of cowherd Nanda, and the giver of prosperity, the enhancer (of the glory) of (the worshipper's) family, the terrifier of Kansa, and the destroyer of Asuras,--and saluted the Goddess--her who ascended the skies when dashed (by Kansa) on a stony platform, who is the sister of Vasudeva, one who is always decked in celestial garlands and attired in celestial p. 11 robes,--who is armed with scimitar and shield, and always rescues the worshipper sunk in sin, like a cow in the mire, who in the hours of distress calls upon that eternal giver of blessings for relieving him of their burdens.
Source : KMG Mahabharata Virata Parva Pandava Pravesha Parva Section VI
Yudhisthira while praying to Ma Durga mentioned her as the one who is the giver of boons and is identical with Bhagwan Sri Krishna. She is as beautiful as moon and her body is as bright as the newly risen sun. She is as beautiful as Shankarsana. She shines as Ma Lakshmi, the consort of Bhagwan Vishnu. She is the one who is pure and she is the one who rescues her devotees from difficulties. She is wealth and prosperity. She is the one who slayed Mahisasura and protected the three worlds.
And Yudhishthira said, 'Salutations to thee, O giver of boons. O thou that art identical with Krishna, O maiden, O thou that hast observed the vow of Brahmacharya, O thou of body bright as the newly-risen Sun, O thou efface beautiful as the full moon. Salutations to thee, O thou of four hands and four faces, O thou of fair round hips and deep bosom, O thou that wearest bangles made of emeralds and sapphires, O thou that bearest excellent bracelets on thy upper arm. Thou shinest, O Goddess, as Padma, the consort of Narayana. O thou that rangest the etherial regions, thy true form and thy Brahmacharya are both of the purest kind. Sable as the black clouds, thy face is beautiful as that of Sankarshana. Thou bearest two large arms long as a couple of poles raised in honour of Indra. In thy (six) other arms thou bearest a vessel, a lotus, a bell, a noose, a bow, a large discus, and various other weapons. Thou art the only female in the universe that possesses! the attribute of purity. Thou art decked with a pair of well-made ears graced with excellent rings. O Goddess, thou shinest with a face that challengeth the moon in beauty. With an excellent diadem and beautiful braid with robes made of the bodies of snakes, and with also the brilliant girdle round thy hips, thou shinest like the Mandara mountain encircled with snakes. Thou shinest also with peacock-plumes standing erect on thy head, and thou hast sanctified the celestial regions by adopting the vow of perpetual maiden-hood. It is for this, O thou that hast slain the Mahishasura, 1 that thou art praised and worshipped by the gods for the protection of the three worlds. O thou foremost of all deities, extend to me thy grace, show me thy mercy, and be thou the source of blessings to me. Thou art Jaya and Vijaya, and it is thou that givest victory in battle. Grant me victory, O Goddess, and give me boons also at this hour of distress. Thy eternal abode is on Vindhya--that foremost of mountains. O Kali, O Kali, thou art the great Kali, ever fond of wine and meat and animal sacrifice. Capable of going everywhere at will, and bestowing boons on thy devotees, thou art ever followed in thy journeys by Brahma and the other gods. By them that call upon thee for the relief of their burdens, and by them also that bow to thee at daybreak on Earth, there is nothing that cannot be attained in respect either of offspring or wealth. And because thou rescuest people from difficulties whether when they are afflicted in the wilderness p. 12 or sinking in the great ocean, it is for this that thou art called Durga 1 by all. Thou art the sole refuge of men when attacked by robbers or while afflicted in crossing streams and seas or in wilderness and; forests. Those men that remember thee are never prostrated, O great Goddess. Thou art Fame, thou art Prosperity, thou art Steadiness, thou art Success; thou art the Wife, thou art men's Offspring, thou art Knowledge, and thou art the Intellect. Thou art the two Twilights, the Night Sleep, Light--both solar and lunar, Beauty, Forgiveness, Mercy, and every other thing. Thou dispellest, worshipped by the devotees their fetters, ignorance, loss of children and loss of wealth, disease, death, and fear. I, who have been deprived of my kingdom, seek thy protection. And as I bow to thee with bended head, O Supreme Goddess, grant me protection, O thou of eyes like lotus leaves. And be thou as boon-giving Truth unto us that are acting according to Truth. And, O Durga, kind as thou art unto all that seek thy protection, and affectionate unto all thy devotees, grant me protection!'"
Source : KMG Mahabharata Virata Parva Pandava Pravesha Parva Section VI
Arjuna prayed to Ma Durga before the Kurukshetra War. Arjuna called her as the mother of Skanda. She is identical with Brahman. She is the consort of Mahadeva. She is endued with every auspicious attribute. She deserves the most regardful worship. She is victory herself. She is the younger sister of Supreme Narayana. She is Saraswati, the mother of Vedas. She is Vedas and Vedangas. She is praised by the Siddhas and Charanas.
"Arjuna said,--'I bow to thee, O leader of Yogins, O thou that art identical with Brahman, O thou that dwellest in the forest of Mandara, O thou that art freed from decrepitude and decay, O Kali, O wife of Kapala, O thou that art of a black and tawny hue, I bow to thee. O bringer of benefits to thy devotees, I bow to thee, O Mahakali, O wife of the universal destroyer, I bow to thee. O proud one, O thou that rescuest from dangers, O thou that art endued with every auspicious attribute. O thou that art sprung from the Kata race, O thou that deservest the most regardful worship, O fierce one, O giver of victory, O victory's self, O thou that bearest a banner of peacock plumes, O thou that art decked with every ornament, O thou that bearest an awful spear, O thou that holdest a sword and shield, O thou that art the younger sister of the chief of cow-herds, O eldest one, O thou that wert born in the race of the cowherd Nanda! O thou that art always fond of buffalo's blood, O thou that wert born in the race of Kusika, O thou that art dressed in yellow robes, O thou that p. 49 hadst devoured Asuras assuming the face of a wolf 1, I bow to thee that art fond of battle! O Uma, 2 Sakambhari, O thou that art white in hue, O thou that art black in hue, O thou that hast slain the Asura Kaitabha, O thou that art yellow-eyed, O thou that art diverse-eyed, O thou of eyes that have the colour of smoke, I bow to thee. O thou that art the Vedas, the Srutis, and the highest virtue, O thou that art propitious to Brahmanas engaged in sacrifice, O thou that hast a knowledge of the past, thou that art ever present in the sacred abodes erected to thee in cities of Jamvudwipa, I bow to thee. Thou art the science of Brahma among sciences, and thou that art that sleep of creatures from which there is no waking. O mother of Skanda, O thou that possessest the six (highest) attributes, O Durga, O thou that dwellest in accessible regions, thou art described as Swaha, and Swadha, 3 as Kala, as Kashta, and as Saraswati, as Savitra the mother of the Vedas, and as the science of Vedanta. With inner soul cleansed, I praise thee. O great goddess, let victory always attend me through thy grace on the field of battle. In inaccessible regions, where there is fear, in places of difficulty, in the abodes of thy worshippers and in the nether regions (Patala), thou always dwellest. Thou always defeatest the Danavas. Thou art the unconsciousness, the sleep, the illusion, the modesty, the beauty of (all creatures). Thou art the twilight, thou art the day, thou art Savitri, and thou art the mother. Thou art contentment, thou art growth, thou art light. It is thou that supportest the Sun and the Moon and that makes them shine. Thou art the prosperity of those that are prosperous. The Siddhas and the Charanas behold thee in contemplation. 4'"
Source : KMG Mahabharata Bhishma Parva Bhagwata Gita Parva Section XXIII
Even Ramayana mentions her as mother of Skanda.
" 'Oh, god Brahma, he who has hypothetically given a Chief of Celestial Army in the form of his potence that god Shiva is undertaking a supreme ascesis, indeed along with Goddess Uma.
Source : Valmiki Ramayana Bala Kanda Sarga 37
She sportingly killd Chikshura. When Chikshura struck on her left arm with a sword , it broke into fragments.
‘“The rishi said, ‘The giant asura, Chikshura, the commander of the army, saw that the soldiers were being killed. Filled with rage, he started to fight against Ambika. In the battle, the asura showered down floods of arrows on the goddess. It was just as if a cloud was showering down rain on the summit of Mount Meru. As if in sport, the goddess severed those arrows. With her arrows, she slaughtered the horse riders and the horses. She instantly severed his bow and the standard that rose up high. When his bow was severed, she pierced his limbs with her arrows. His bow was severed. He was without a chariot. His horses were killed. His charioteer was killed. Wielding a sword and a shield, the asura rushed towards the goddess. With the sword, sharp at the edges, he struck the lion on the head. With a great deal of force, he struck the goddess on her left arm. O son of a king! 801 As soon as the sword touched the arm, it shattered into fragments. His eyes turned red with rage and he seized a trident. The giant asura hurled this towards Bhadrakali. It blazed in its energy, like the solar disc in the sky. When she saw that the trident was descending, the goddess hurled her own trident and it shattered the trident and the giant asura into one hundred fragments.
Source : Markandeya Puran ch 80 translated by Bibek Debroy
An asura Chamara attacked her with a spear but she neutralized it with “Humkar”.
‘“‘The general of Mahisha’s army was Chamara, the afflicter of the gods. When he saw that the immensely valiant one was dead, he advanced astride an elephant. He quickly hurled a spear towards the goddess Ambika. When she uttered humkara, 802 that spear fell down on the ground, losing all splendour.
Source : Markandeya Purana ch 80 translated by Bibek Debroy
Chamara was later killed by her lion.
The enemy of the deer struck him with force and brought him down. With a blow of its paw, it severed Chamara’s head.
Source : Markandeya Purana ch 80 translated by Bibek Debroy
She butchered one asuras after another with trees, boulders, sword, her teeth ,fists , mace, arrows etc
‘“‘In the battle, the goddess killed Udagra with boulders and trees. She brought down Karala with her teeth, fists and palms. The goddess angrily crushed Uddhvata by bringing down her mace on him. She killed Baskhala with a javelin and Tamra and Andhaka with arrows. With her trident, the three-eyed Parameshvari killed Ugrasya, Ugravirya and Mahahanu. With her sword, she severed Bidala’s head from his body. She used her arrows to convey Durdhara and Durmukha to Yama’s eternal abode. Kalaratri brought down Kala with Destiny’s staff. She struck Ugradarshana with a fierce blow of her sword. In the battle that was like a festival, she severed Asiloma with her sword. At this act of the goddess, the ganas and the lion started festivities, exclaimed “victory” and exultantly slapped themselves.
Source : Markandeya Purana ch 80 translated by Bibek Debroy
She finally killed Mahisasura after a fierce battle.
She pressed down on his throat with her foot and struck him with the trident. Restrained by the valour of the goddess, who was pressing down on the buffalo’s throat with her foot, he could only half emerge from the buffalo’s mouth. Though only half of his body could emerge, the giant asura continued to fight. With a large sword, the goddess severed his head and brought it down.
Source : Markandeya Purana ch 80 translated by Bibek Debroy
She is unmatched and even Tridevs can’t describe her prowess.
Your powers are unmatched. The illustrious Ananta, Brahma and Hara lack the powers to describe them.
Source : Markandeya Purana ch 81 translated by Bibek Debroy
She is the Supreme Prakriti.
You cannot be comprehended by Hari, Hara and the others. You are the refuge for everything. Everything in the universe has originated from your parts. You are the original one. You are supreme Prakriti, without any form.
Source : Markandeya Purana ch 81 translated by Bibek Debroy
She reduced Dhrumlachona to ashes with “Humkar”.
Thus addressed, the asura Dhumralochana rushed towards her. However, with a humkara, Ambika reduced him to ashes.
Source : Markandeya Purana ch 83 translated by Bibek Debroy
She as Ma Kali killed Chanda and Munda and came to be known as Chamunda.
Astride the giant lion, the goddess rushed towards Chanda. She seized him by the hair and severed his head with her sword. Having severed the head of the Indra among daityas, she emitted an exceedingly terrible roar. The three worlds were terrified at this loud roar. On seeing that Chanda had been brought down, Munda rushed forward. She angrily struck him with the khatvanga and brought him down on the ground. The remaining soldiers saw that Chanda and the extremely valiant Munda had been brought down.
Source : Markandeya Purana ch 83 translated by Bibek Debroy.
Seeing that Kali had brought the two large asuras, Chanda and Munda, the fortunate Chandika addressed her in these beautiful words. The goddess said, “O goddess! Since you have seized the giant asuras, Chanda and Munda, and have come, you will be famous in the world as Chamunda.”
Source : Markandeya Purana ch 83 translated by Bibek Debroy
Note : Ambika, Kali etc are different forms of Mata Parvati. Ambika emerged from sheaths of Mata Parvati, while Kali emerged from the base of forehead of Ambika. Ambika and Chandika are same while Chamunda and Kali are same.
Since Ambika issued from the sheaths in Parvati’s body, all the worlds used the name Koushiki to sing about her. 823
Source : Markandeya Purana ch 82 translated by Bibek Debroy
When she had emerged, Parvati turned dark. She resides in the Himalayas and is known as Kalika.
Source : Markandeya Purana ch 82 translated by Bibek Debroy
Ambika became very angry with the enemy. Because of her rage, her face turned as black as ink. When she furrowed her brows, Kali, terrible to behold, emerged from the base of her forehead, wielding a sword and a noose.
Source : Markandeya Purana ch 84 translated by Bibek Debroy
Mahadeva acts as her messeger , hence she is known as Shivadutti.
Thus, the goddess appointed Shiva himself as her messenger. Thereafter, she became famous in the worlds by the name of Shivaduti. 836
Source : Markandeya Purana ch 85 translated by Bibek Debroy
Whenever blood from the body of Raktabija used to fall on ground/earth, a new one would emrge , hence Ma Kali streched her tongue and prevented blood from falling on ground while Ma Ambika slayed Raktabija.
Saying this, the goddess struck him with a trident and Kali received Raktabija’s blood in her mouth. At this, he struck Chandika with his club. However, despite the blow of the club, she did not feel the slightest bit of pain. Struck by her, a lot of blood started to flow from his body. But all of this was received by Chamunda in her mouth. From the flow of blood, large asuras were generated inside her mouth. But Chamunda devoured them and drank up the blood. The goddess struck Raktabija with her trident, chakra, arrows, sword and double-edged sword and Chamunda drank up the blood. O lord of the earth! Struck by those weapons, Raktabija, the giant asura, became bereft of blood and lay down on the ground, lifeless. O king! The gods were filled with unmatched delight.
Source : Markandeya Purana ch 85 translated by Bibek Debroy
She killed Nishumbha.
Nishumbha seized a club and rushed towards Chandika with great force, surrounding himself with daitya soldiers and desiring to kill her. As he descended, Chandika quickly severed the club with her sharp sword. He seized a spear. With that spear in his hand, Nishumbha, the afflicter of the immortals, rushed forward. However, Chandika powerfully pierced him in the heart with her trident. When his heart was shattered, another man emerged from inside it. He was immensely strong and immensely valiant. “Wait,” he exclaimed. But as he was emerging, the goddess laughed out loud. She severed his head with her sword and it fell down on the ground.
Source : Markandeya Purana ch 86 translated by Bibek Debroy
She killed Shumbha after a fierce battle. I am just quoting a part of it.
The daitya and Chandika wrestled with each other there. At first, 844 this caused great amazement among the Siddhas and the sages. For a very long time, he wrestled in this way with Ambika. After this, she picked him up, whirled him around and flung him down on the ground. Though he was flung down on the ground in this way, the evil-souled one rose up. He raised his fists and rushed forward, desiring to kill Chandika. The lord of all the daitya subjects advanced. But the goddess pierced him in the chest with her trident and felled him on the ground. Mangled by the points of the goddess’s trident, he lost his life and fell down on the ground.
Source : Markandeya Purana ch 87 translated by Bibek Debroy.
She is called Durga for two reasons :
(i) She protects her devotees from troubles and distress like a fort(“Durg”) protects one from enemies.
And because thou rescuest people from difficulties whether when they are afflicted in the wilderness p. 12 or sinking in the great ocean, it is for this that thou art called Durga 1 by all.
Source : KMG Mahabharata Virata Parva Pandava Pravesha Section VI
(ii) She is the slayer of Durgamasura.
At that time, I will slay the giant asura known as Durgama. Therefore, I will be famous under the name of the goddess Durga.
Source : Markandeya Purana ch 88 translated by Bibek Debroy
She will slay fierce asuras in Himalayas and will be famous as Goddess Bhima.
Next, I will assume a terrible form in the Himalayas, to devour the rakshasas and save the sages. At that time, all the sages will respectfully lower their bodies and praise me. I will be famous under the name of the goddess Bhima. 859
Source : Markandeya Purana ch 88 translated by Bibek Debroy
She will slay Arunaksha in the form of a bee and will be famous as Goddess Bhramari.
For the welfare of the three worlds, I will assume the form of a bee and with innumerable other bees, will slay him. All the worlds will then praise me under the name of Bhramari. 860
Source : Markandeya Purana ch 88 translated by Bibek Debroy
Hence Skanda Mata is the Supreme Goddess and she protects her devotees from miseries and distress and blesses them with health and prosperity. She is the protector of the three worlds and destroyer of Asuras.