Aggron's Fire Red and Leaf Green Pokedex entry says, "It claims a large mountain as its sole territory. It mercilessly thrashes those that violate its space."
Aggron's Mountain
All who enter his mountain lair.
From their body, the skin will tear
With his claws, as strong as iron
Even grown men, will be cryin
You will not, leave this place.
Without knowing, what's beneath your face.
You will drown, in your blood.
While he stomps, you in the mud.
There is no way out of here.
Your final wish, will soon be clear.
To die real fast, and take away your fear.
The sounds are louder, he is almost near.
You cannot run, you cannot hide.
All who have come, will surely die.
If you come across his mountain path,
there is no escape from Aggron's wrath.
- originally taken from
http://creepypasta.wikia.com/wiki/Aggron%27s_Mountain