There is no full powered Galactus my friend his hunger can never be fully satisfied,However fed on 4 planets he killed two celestials(with some help from Franklin) and the Anvil weapon.but he gave 4 celestials a hell of a fight on his own!He even blocked one of their eye beams and scattered the 4 of them(even Odin in the Destroyer with almost the entire amount of Asgardian gods did nothing close to this)if g would have ate his home world he could beat a whole Celestial host easy I.M.O.
I am a big Galactus fan ,and one of his worst loses was to the avengers,f.f,and Dr.strange.he was so weak from not feeding Strange cast a spell that confronted him with the ghosts of the trillions of people he killed.His mind almost shut down,The thing used Reeds powers as a sling shot and actually ko`ed Galactus.Reed relented and built a device to save Galactus(as his death means the eventual end to the universe)So powersd by Thor`s hammer they save him,truly a low point for mighty Galactus!
Never let anyone else define you. Don't be a jerk just to be a jerk, but if you are expressing your true inner feelings and beliefs, or at least trying to express that inner child, and everyone gets pissed off about it, never NEVER apologize for it. Let them think what they want, let them define you in their narrow little minds while they suppress every last piece of them just to keep a friend that never liked them for themselves in the first place.
He loses power the longer he goes with out feeding,thats why he is the perfect plot device.He could beat Celestials or lose to a group of heros on earth depending how well fed he is!