Your question is a very good one, as in how will Mahdi prevail (and basically what attributes should he have to know if he is the true Mahdi)
So God has sent 124000 prophets and all died, killed, poisoned. And he wants to show to everyone that eventually:
And We wanted to confer favor upon those who were oppressed in the land and make them leaders and make them inheritors
"Seek help through Allah and be patient. Indeed, the earth belongs to Allah . He causes to inherit it whom He wills of His servants. And the [best] outcome is for the righteous." Al-A'raf 128
God has allowed every nation to rule, so each nation shows its true face. There has never been a single nation on planet which can claim their nation was a just nation (except for the nations governed by the prophets).
Now it is the time for God to show he's above ALL. His nation is just.
And to precisely answer your question:
And we rained down on them a shower (of brimstone): Then see what was the end of those who indulged in sin and crime! Al-A'raf 84
And to Allah belong the soldiers of the heavens and the earth. And ever is Allah Exalted in Might and Wise. Fath 7
God has control over animals, wind, rain, earth, etc, I did I forget to mention the angels who will aid him (as already done in the battle of Badr)?
[Remember] when you asked help of your Lord, and He answered you, "Indeed, I will reinforce you with a thousand from the angels, following one another." Al-Anfal 9
So a drone could be knocked down by wind, or a terrible rain ( God can create rain of non-water type), tornado, thunderbolt, a good number of birds, angles or other means.
When the Mahdi comes, his first moment is:
While he has the Ka'ba to his back he will say:
بَقِيَّتُ اللَّهِ خَيْرٌ لَّكُمْ إِن كُنتُم مُّؤْمِنِينَ
What remains [lawful] from Allah is best for you" Hud 86
بقیه الله is one of the many titles of Mahdi. But when he says such, the entire world will hear him—leaving no doubt from anyone. God's media is universal. His message is more visible than the sun. Since it's a non-human act, whatever the media says won't make a difference.
People either believe or not. Either they become humble or not.