Sentry has lots of versatility. Hes able to get beat up by a wide variety of characters in all sorts of creative ways. My favorite being his own wife who shot him with a gun that was casually left behind by a teammate.
I am a little confused at to how much more powerful Genis was when he was insane compared to normal. The way he's talked about I'm led to think he was High-Skyfather level.
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“Where the longleaf pines are whispering
to him who loved them so.
Where the faint murmurs now dwindling
echo o’er tide and shore."
-A Grave Epitaph in Santa Rosa County, Florida; I wish I could remember the man's name.
Im starting to think Spider-Man made up the whole "stalemating Galactus" thing. Like hes trying to turn Sentry into Marvel's chuck norris. I mean regardless of the guy's mental state, his physical attributes should stay the same, which makes me wonder why his face was melted by Marvel Boy's gun.
If you haven't noticed his power fluctuate greatly.
The condition of him defeating Galactus was never revealed so it could have been a very weakened Galactus considering most of Galactus appearances are when he is weak. Even than yes it's a big stretch that Sentry would stalemate him but it could happen.
But there is a lot of room to makes this character like 100X more powerful using personalities like the "Void".