This is how Nightmare Moon arrives on the Unicron Star and Rebel meeting goes in My Little Pony Transformers: Return of the Jedi.
[We see the shuttle of Nightmare Moon approaching]
[The shuttle lands in the docking bay]
[Nightmare Nova and Commander Chrysalis watch as the door opens]
[Nightmare Moon steps out as Nightmare Nova bows]
Nightmare Moon: Rise, my apprentice.
[Nightmare Nova rises]
Nightmare Nova: The Unicron Star will be complete on schedule.
Nightmare Moon: You have done well, Lady Nova. And now I sense you wish to continue your search for young Sparkle.
Nightmare Nova: Yes, my Master.
Nightmare Moon: Patience, my friend. In time, she will seek you out. And when she does, you must bring her before me. She has grown strong. Only together can we turn her to the dark side of the Force.
Nightmare Nova: As you wish.
Nightmare Moon: Everything is proceeding as I have foreseen. [laughs wickedly]