My bet's on Extremespeed, if we go by the original games' lore. There was a surfing Pikachu in them, and there's an Extremespeed Dratini you can get for answering some questions to an elder in Dragon Cave or whatever it was called. The sad part is, it won't carry over to Dragonite, and even if it did, it's as good as Hyperbeam anyway, it's a normal type move.
GamePress
Dratini - exclusive move
What exclusive movement do you think Dratini will have during the event?
I think that he will have Draco meteor (maybe Dragonite during this time too)
