There are 2 canon stories: 1. They were damaged, some of them were dead by Creation and his army, they ran but they saw the portal opened and they fall in, and they wake up in the outside world of FAGFS Universe. 2. They were fighting Creation and his army, and Creation pressed the button, causing the gas to wipe out Greddy and his gang, and ended up in parts and service, they figured out what is going on.
C2A, @tyrashon can make his own versions of Blueberry and his gang since technically their Georgiger characters.