Full powered Galactus? There is no such thing, Galactus has no upper limit as to how powerful he can become. If Galactus devoured a universe, I am pretty sure he could wipe out Asgard. If not why is he considered to be a peers of LT, and Eternity. Why would he be essential? Asgard is not essential if it was why did it die? Tyrant would win at full power, but I am not completely convinced of him winning at his lower levels. I would say stalemate for one and a decisive win for two.