"If you stat it, they will kill it"
I think the point of the tarrasque is that it cant be killed. It can be defeated, but it will come back for ever and ever. Its a "God" of nature I would say. It sleeps for 250 years and then wake up, destroy a few kingdom and them burrow back to a lair for an another 250 years. Its a "Natural" phenomena like a Tornado or a Tsunami.
And even if its killed, I'm pretty sure an another one would hatch soon after from the bottom of the earth and then come to earth.
You do not kill the tarrasque. You survive it.