RAPID SENTRY Q & A: Was Sentry beating Molecule Man PIS?
No, it wasn't PIS.
Again, PIS stands for Plot Induced Stupidity, which is when something stupid happens in a story, which is clearly only there to progress the story fast, without too much additional thought behind it.
An example would be Deathstroke being able to stab a Flash, simply by knowing him for so long and being able to predict his movements. Pretty much every Flash has feats, where Deathstroke should be a statue for a Flash all the time and therefore such a PIS instance shouldn't happen in the first place... But it has to so that Deathstroke can do [proceed with the plot].
Now why was Sentry beating Molecule Man not a PIS instance? Because there was a lot behind it. Sentry defeating the Molecule Man in a fight served as character development and long term plot progression:
1. Sentry was coming up with new powers every other day, when he needed them and sometimes he was wondering about them. Like for example him being able to resurrect his dead wife or him being able to resurrect himself, when he had died.
We didn't know how he was able to do all those things. Prior to his fight against the Molecule Man, we assumed that his powers were solar or psionic based, but having solar / psionic based powers, doesn't allow you to resurrect the dead.
Once Sentry encountered the Molecule Man and got destroyed by him a couple of times, he then resurrected himself again under his own power and had finally realized how he was able to do what he was doing... By controlling the molecules, which was the same thing Molecule Man was doing.
2. Sentry had defeated the Molecule Man and established himself further as an absolute monster, when it comes to power levels... which came in handy, considering, that he was supposed to be the final boss for the Siege event.
It's not like the writer of that story one day thought up an arc, where Molecule Man would appear in a Dark Avengers comic, where the Dark Avengers would then beat him... You know, to stretch it out and sell more comics... No, there were years of work behind all of that and the Sentry was always supposed to beat the Molecule Man and at the same time become more and more schizophrenic and finally turn into the Void himself and attack Asgard and the Avengers.
RAPID SENTRY Q & A: Is the Sentry as powerful as HoM Scarlet Witch?
No. He has never displayed power on her level.
HoM Scarlet Witch was warping the reality on a universal plus scale. Sentry's greatest feats are all on a planetary plus scale. He has erased the memories of billions and billions and billions of beings, destroyed planets while holding back and stuff like that. He is probably capable of doing much more than that, but probably nothing a skyfather like Odin wouldn't be able to replicate and HoM Scarlet Witch would take Odin out with three words.
In the HoM storyline Scarlet Witch even affected the Sentry like everyone else. If he was on her level, one would assume that he would have been able to fight against the influence of her power:
http://imgur.com/a/Un1an
Although it's interesting to note, that Sentry didn't have to deal with the Void, before he got his powers. In the reality HoM Scarlet Witch had created for him, he was powerless, but he was still dealing with the Void.
RAPID SENTRY Q & A: How powerful is the Sentry POTENTIALLY?
The Sentry is weird, man... And I don't mean as a character, but rather as a being in the Marvel universe.
No one really knows what he is, not even Marvel's smartest men and women.
Molecule Man, the guy, who has experienced all the molecules in the multiverse had no idea what the Sentry was made of and the Skrulls couldn't copy his powers, because they didn't understand them. Actually, no one was ever able to get a good grasp of Sentry's powers and limits, not even he himself.
Sentry has no physical weaknesses and can't die even when he tries to.
While that may not answer the question, it still goes on to show, that there is something wrong with the Sentry. Something unexplored. Right now he can't be put in a box and labled. He simply can't.
A character like Thor is already well established and can't really pull off something stupid, which we're then supposed to make sense of and view that as his new status quo.
When it comes to the Sentry however, he can do whatever he wants. At one day he is punching Namor around and the next day he is beating the Molecule Man and it makes total sense in a nonsensical way.
Did Sentry stalemate Galactus in a 1 on 1? I don't know, nor do I really care, but... would you be shocked if he has? I certainly wouldn't. The Sentry has a track record of pulling off the weirdest stuff out of nowhere and that's a good thing, because it makes him more mysterious and interesting.
POTENTIALLY he could be the most powerful man in existence:
http://i.imgur.com/ot3gNhR.jpg
RAPID SENTRY Q & A: Was Sentry really one of the first heroes in the Marvel universe, or did he change the reality so that it would only look like that?
The "theory" with the Sentry unknowingly forcing himself into everyones life is based on a non-canon book called THE AGE OF THE SENTRY.
Canon wise, the Sentry was one of the first heroes in the Marvel universe and knew many other Marvel characters. He had to "erase himself from existence", because of the Void.
RAPID SENTRY Q & A: How long would have an unstable Sentry lasted if World War Hulk didn't hold back?
Eh... Hulk wasn't holding back. That's one of those Hulk fanboy myths, because they don't want their green goliath to look worse by going all out against an unstable Sentry and still only pulling off a tie / somewhat win.
They think that Hulk was holding back due to some statements from Cho and himself, where he said, that he was pulling his punches... And they use those statements to transfer it to absolutely EVERY other moment in the World War Hulk event, no matter how flawed the logic behind it is.
1. Sentry had turned into the bad guy by the end of the World War Hulk event. He had lost control over his energy emission and was at the verge of destroying everything around him. Tony Stark tried stopping him with the use of his satellites, but Hulk laughed at him and stated, that machines wouldn't be able to stop the Sentry and jumped back into the fight to face the Sentry:
http://i.imgur.com/Gdy8gZ1.jpg
http://i.imgur.com/6THVySS.jpg
Are you telling me, that the Hulk, who is facing a Sentry, who is on the verge of destroying everything in a matter of moments, still holds back his punches? Logically speaking he must have went all out to stop the Sentry as fast as he could, otherwise the Sentry would have destroyed everything.
2. But okay, maybe that's not proof enough for you and maybe you're right, since it could be viewed as only my way of interpreting that particular moment... so here is something else:
http://i.imgur.com/7o1sbYm.jpg
The bio of the event states that both men unleashed their full power and transformed back to their human forms in the end. The Hulk wasn't holding back. He went all out and unleashed everything he had in that form of his.
My common sense is tingling, YO!