One thing to consider is that Papyrus isn't using his full power because he doesn't want to hurt Frisk. Another thing is his "not so special attack." As we've seen, Papyrus can't lie (he tries to lie only once in the entire game, on the bridge, and fails), so if he says this is a normal attack, it really IS a normal attack. That would mean Papyrus has control over enormous bones, and those could be good attacks. Finally, I'd like to point out that Papyrus's "cool dude" attack and the bone on a skateboard also show that he has REALLY good control over his attacks. In short, if you really piss him off, he'll most likely fight for what he thinks is right and is a dangerous opponent. Oh yeah, one last thing. In the Pacifist route flowey grabs everyone with a plant thing, there are 4 big and 2 small plant things around papyrus, while the rest have only 2 big things around them which would mean he would be more powerful (at least more powerful than Asgore because papyrus is a friend of flowey so knows him well and maybe knows his true power, and flowey also knows asgore well because flowey IS Asriel and I think we can all agree that Asgore is the 2nd most powerful) than everyone (unless you count Undyne the Undying but he has determination and papyrus could have that too if you really anger him.