Monster Hunter games aren't known for their amazing narratives. You boot up a monster hunter game because they're fun to play, never to hear an interesting plot.
But there have been some interesting stories in the past-and what's more, they've been told in some really fascinating ways. A great example is Monster Hunter 4, which told the story of a rivalry with the potential to change the fate of the world.
But is it the best story told in a monster hunter game? Well...
Link to Ayyvian's video showcasing green plesioth's move in MHS2: https://www.youtube.com/watch?v=y1wD1mNiXkU