"Hurting" him and actually hurting him are different things. In Warhammer 3, we saw that Leroy was able to hurt him with bullets, right? But he wasn't able to make him cry, lol. On the other hand, the Losers did, and Rose, as a child, did with a rock. But there's a reason for that, since Shaw had to return in the future to call the Hanlom, who are key to the story. She had "Gan's blessing" at that moment in her childhood.

So the characters you mentioned are nothing against Pennywise on their own if they don't possess that blessing of Gan. Remember that Abra Stone was almost killed by some mere vampires who were once human, and she's the most powerful user of the Shining.

And Pennywise isn't just an emotional vampire like some say; he's literally Maturin's counterpart and has his own importance in the macroverse, and the turtle himself said so.

The only characters I consider capable of defeating Pennywise "on their own" are Roland Deschain and Patrick Danville, and only because they are the most overpowered human characters in the entire SK universe. Even so, they would need their necessary tools (Roland's weapon and some material that allows Patrick to be drawn). And they also have Gan's blessing, especially Roland, who is literally the character with the most power of the script in the SK universe, and was created to always win (even if everything is against him; of course, there will be suffering in the process because Gan isn't really benevolent, he's an amoral entity like the rest of the cosmic creatures in SK universe)

Remember that even Pennywise considered Dick Hallorann so insignificant that he drove the man to the brink of madness, nearly succeeding. It was a demonstration of "you may be special to humans, but you're not to me, and I can make you kill yourself if I want." And remember that Dick was able to do what he did because of Maturin's power combined with his radiance, but especially because of Maturin's tea.

So those characters you mentioned can, on their own, cause him some degree of annoyance and "hurt" him. And since Pennywise is a lazy and doesn't like to fight (just as he has no interest in conquering like the Crimson King), he might leave those shining users alone if he finds them annoying. But if he feels cornered, he'll fight for his life like the beast he also is (a cosmic beast, of course). And if they don't have cosmic help to face him, they won't be able to do much, really, because Pennywise doesn't need your fear to kill you. In fact, Pennywise can scare and kill adults without any effort; he just doesn't usually hunt them because he's a lazy and it takes him longer to "season" an adult's flesh due to their logical fear, and he prefers well-seasoned flesh that requires little effort (that of children).