Is Vegnagun from x-2?Now I understand what you meant.
But no.My theory is not disproofed because we never fought "Bevelle"´s machines(that little ones that throws rocks and stumps were not created on "Bevelle") on ffx.
The ones we fought are the ones in ruins.They were created on the city submerged on the mooflow.
Which led me to the question.Who destroyed these?Sin?
Oh,they were able to beat all of zanarkand´s aeons (including the final one) and can´t defeat a stupid sea monster (which Yuna´s aeons defeat easily)?