This is how Megatron's resurrection and Megatron talks with the Fallen goes in My Little Pony Transformers: Revenge of the Fallen.
[We then see a boat]
[Ravage lands on the boat]
[The Constructicons Scrapmetal, Mixmaster, Long Haul, and Rampage jump into the Laurentian Abyss to Megatron's corpse, Ravage leading the charge]
[Some submarine ponies are confused as to what is going on]
[The Decepticons arrive at Megatron's corpse]
[Ravage lets out Scalpel]
[Scalpel examines Megatron]
Scalpel: Need parts. Kill ze little one!
[Long Haul and Rampage attack Scrapmetal]
[Scrapmetal yells in agony]
Scalpel: The shard make Energon.
[He plunges the shard into Megatron's spark]
[Megatron comes online jets upward to the surface and crashes the submarine monitoring him]
[Megatron flies out of Equestria's atmosphere and into space]
[He reaches the wreckage of the Nemesis]
[He lands and calls out for Starscream]
Megatron: Starscream, I'm home.
Starscream: Lord Megatron, I was so relieved to hear of your resurrection.
Megatron: You left me to die on that pathetic insect planet!
Starscream: Only to help spawn our new army. The Fallen decries it. After all in your absence, someone has to take command.
Megatron: [slams Starscream against the wall] So disappointing.
Starscream: [choking] Hatchlings, hatchlings! Careful, fragile.
Megatron: Even in death there is no command but mine.
[A hatchling falls out and gives a death cry]
[We then see Megatron meeting with the Fallen]
Megatron: My master, I failed you on Equestria. The Allspark is destroyed and without it, our race will perish.
The Fallen: Oh, you have much to learn, my disciple. The Cube was merely a vessel. Its power, its knowledge can never be destroyed. It can only...transform.
Megatron: How is that possible...?
The Fallen: It has been absorbed by the alicorn girl and her friends. Its power and knowledge are in their minds. The key to saving our race now lies within their minds.
Megatron: Well, then, let me strip the very flesh from their bodies.
The Fallen: And you will, my apprentice, in time. For a millenia I have dreamt of my return to that wretched planet, where I too was once betrayed by the Primes I called my brothers. Only a Prime, an Alicorn, and an ancient hybrid can defeat me and now only one ancient hybrid remains.
Megatron: The Indominus Rex from Jurassic World. She protects the alicorn.
The Fallen: Then the I-Rex will help us find her. And revenge will be ours.
Starscream: We have the alicorn in our sights. She will not escape us. Without more Energon, the Hatchlings will keep dying.