The characters in the game don't themselves have the power to beat omega weapon. They require the use of Guardian Forces to junction magic and to have the abilities to use magic and items and commands (like revive or recover), Without the Gfs and junctioning the party cannot beat Omega Weapon. Therefore the characters themselves are not that powerful and if one tries to conclude that adel has the power of the 8 individuals and only 3 are required to beat omega, it is not valid because the characters require the help of gfs to beat omega.