Do characters need flaws?
Question: In the book I'm currently planning I have some angel characters. I would like to know if I have to create minor or major flaws or any at all.
Answer: I think it would be pretty difficult to create a main character who is flawless. It's hard for readers to relate to flawless characters. They seem so unlike us.
Flawless people also seem so unlike the people we encounter in the world.
You sometimes come across Guardian characters who seem nearly perfect, but even they have tiny flaws. Obi wan Kenobi has a mild dislike of technology. Dumbledore has certain ambitions he isn't always able to hold in check. Gandalf... well he knows so much he sometimes forgets what he knows.
Your challenge, I suspect, with angelic characters is that people expect them to be morally perfect. But do they have to be perfect in every other way? Do they have to be all-powerful?
It's actually an old philosophical dilemma: if the universe contains a race of perfect, all-powerful entities (or even one), why does everything seem so imperfect?
Or, to put it another way, if there were a source of perfection in the universe, there would be no problems. Yet, stories are about problems. They are about situations that are less than perfect, and about less-than-perfect people trying to figure out how to cope. If there's no problem, there's no story.
So I think your angelic characters must at least have some limitations. If they are all-wise, all-knowing, and entirely benevolent, then perhaps their power is limited. If they are all-powerful, then there must be flaws in their characters. And that means they have challenges, frustrations, and the capacity for failure.
Angels or gods in literature and mythology always seem to be possessed of human-like faults, no matter how powerful they are. Otherwise, their stories would make for dull reading.