Accounts on the King Messiah [Hazrat Mahdi (pbuh)] in the Zohar

Only a few number of young people will gather around him:
… THOSE WHO ARE CALLED in the verse 'CHILDREN' ('YOUNG'), will gather to him. THEY ARE FEW IN THE WORLD, and in the merit of school children, the strength of Mesiah will grow greatly. And this is the secret of the young in the verse. (15. Shemot: 15. The coming of Messiah, verse 130)

Rise of a star from the east side:
After 40 days, the pillar will stand from the earth to the heaven before the eyes of the whole world, and Messiah will be revealed. THERE WILL ARISE FROM THE EAST SIDE A STAR that will glow with variety of colors, and seven other stars will surround that star and will war with it on all sides, three times a day up to seventy days. And all the people of the world will see. (15. Shemot: 15. The coming of Messiah, verse 101)
Then the seventh window will be opened to the whole world, and its star is the star of Jacob. This is what Bila'am said, "There shall come a star out of Jacob" (Bemidbar 24:17), and this star will illuminate for forty days. When King Messiah will be revealed and all the nations of the world will gather before him, this passage will be fulfilled." (Yeshayah 11:10). (21. Trumah: 86. The stars, verse 860)

The disappearance of King Messiah [Hz. Mahdi (pbuh)]:
After seventy days, that star will be hidden and Messiah will be concealed for up to twelve months. Then the pillar of fire will return as originally, and in it Messiah will be concealed, and that pillar is invisible. (15. Shemot: 15. The coming of Messiah, verse 102)

Many signs will be seen with the coming of King Messiah [Hz. Mahdi (pbuh)]:
When Messiah awakens, so many other signs and miracles will be aroused in the world. (15. Shemot: 15. The coming of Messiah, verse 106)

In the time of King Messiah [Hazrat Mahdi (pbuh)] the holy treasures will be revealed:
All the celestial treasures and all the hidden mysteries will not be revealed until the days of King Messiah. (19. Yitro: 19. "and all the people saw the voices", verse 299)

There will be pressure on real pious people and good people:
Before the coming of the Messiah, the Mishnah [Torah interpretation] scholars, sages of supernal wisdom, scholars of Kabbalah, scholars of the secrets in the Torah, will have a time of hardship, as they have nothing to support them. (32. Acharei Mot: 36. The seventy sounds of a woman in labor, verse 211)
At that time, She is opened to give birth to Messiah. This is owing to the pain and distress of the pious, men of good qualities, sages of secrets of the Torah, people of humility and shame, of fear and love, of kindness, men of valor, fearing Elohim [God], truthful men, who despise bribes, for whom it is a time of poverty. In the times in which the son of David [King Messiah] will come, a valiant men will go circulating from city to city but will not be shown favor. Those that fear sin will be despised. (32. Acharei Mot: 36. The seventy sounds of a woman in labor, verse 213)

Before the emergence of King Messiah [Hz. Mahdi (pbuh)], there will be pains in the world and in Israel:
At the time of the revealing of Messiah, the inhabitants of the world will find themselves in one distress after another and those who hate Yisrael will get stronger. (43. Balak: 47. In the time of Messiah, verse 505)

King Messiah [Hz. Mahdi (pbuh)] will accept all the pains for Allah's pleasure:
… There is one temple called the temple of the sick. The Messiah enters that temple, and calls upon all the diseases, the pains and agonies of Yisrael to descend upon him. And they all descend upon him… This is the meaning of "he has borne our sicknesses..." (Isaiah 53:4). (25. Vayakhel: 24. The firmaments over the Garden of Eden, verse 336)

The name Lion:
… UNTIL THE APPEARANCE OF MESSIAH, THE SON OF DAVID, WHO IS CALLED 'A LION'... (20. Mishpatim: 17. A spirit ascends and descends every night, verse 475)
The verse, "May he have dominion also from sea to sea, and from the river to the ends of the earth" (Tehilim 72:8), will be fulfilled in Messiah… The flag of Messiah, the son of David, will come, being of Judah, with a lion marked upon it... (20. Mishpatim: 18. verse 483)

King Messiah [Hz. Mahdi (pbuh)] will be the means for the faith of the entire world:
Oh, holy pious one, glad is the one who will hear from the mouth of Messiah. The sweet voice of his discourse is in the concealed matters of the Torah that he will explain… all congregate around King Messiah. And he will explain to them the Torah matters. Through the sweetness of his words and through desire, they get elevated to the Heavenly Yeshivah... (40. Shlach Lecha: 16. Reading of the Torah, verse 142)

Not everyone will be able to appreciate King Messiah [Hz. Mahdi (pbuh)], he will be recognized only with the light of faith:
The Congregation of Yisrael is adorned with the crown that the Holy One, blessed be He, is going to crown King Messiah. That crown is decorated and engraved with the Holy Names. Everyone who merits it in this world, merits to see Messiah with the perfection of that crown. (21. Trumah: 10. "The watchman said, 'The morning comes'", verse 98)

In the time of King Messiah [Hz. Mahdi (pbuh)], idolatry will come to an end and true religion will reign:
… just as the idolatrous nations of the world will hide when Messiah is revealed, as it is written: "And they shall go into the holes of the rocks" (Yeshayah 2:19); "and in the holes of the rocks" (Yeshayah 7:19). (44. Pinchas: 85. Additional Nefesh, additional Ruach, additional Neshamah, Verse 573)
Close to the days of Messiah, the window with this star shall rule the world. Therefore, wild animals will rule the world and new evil species will be formed one after the other, and the children of Yisrael will be in distress. When they will be pressed in the darkness of exile, the Holy One, blessed be He, will light up for them the light of day, which is redemption, and the supernal holy ones will accept the kingdom. Rulership will be annulled from the idol-worshipping nations... Then will be fulfilled: "Moreover the light of the moon shall be as the light of the sun..." (Yeshayah 30:26). (21. Trumah: 86. The stars, Verse 859)