>>50877357So its pretty much down to trying to find out how big the giant xurkitree's are compared to how big Eternamax Eternatus is.
Eternatus looks to be around mountain size or at most around the size of the Tower summit. Bulba also says it might be the tallest pokemon ever.
But what about the Xurkitrees? They're gigantic enough for their cable limbs to be the ground, large enough to be visible from such a far location and could also be mountain size?