Mistake in elements
I think there might be a minor mistake in what element this wyvern uses as the footage here ( https://www.youtube.com/watch?v=74Oio-Dlpm4 ) shows it using the dragon element not fire
https://youtu.be/iAjcLUSYcXw at 1:46
You can see Egyurasus making Fire Breaths along with Guanzorumu... This Flying Wyverns can use Fire... However, you've right too, but in the video that you've linked, that was a unique "Special Event" (or whatever is called) Guanzorumu, so i don't know how should be handled...
EDIT: i don't even know if Egyurasu can be considered a small monster or a "part of the scenario" since i haven't seen someone who have killed an Egyurasu!