Iris and Misty have that tomboyish personality in common, yes, but Iris and Misty doesn't have the same personality. Iris is more immature, she consider herself to be surperior to others, and she protects her pride by putting others down and calling them stuff in order to prove that she's the one and only. I think that is a rather unique personality, and I also love it, since I think it's absolutely hilarious when she goes out into action and teases Ash/Georgia. If you don't think that's unique, then please name another character that has the same traits.
As for Dawn, just no. I think she's a lot like Ash, and I don't think her personality is very different from others, more than her struggling to actually achieve victory in contest. But that's just bland and boring, 'cause I think that her training is pretty much the same all the time and only gets repeated. And I do not think that you can say that clothing style makes Dawn more unique than others, really. It's typical clothes for a girl, nothing special, and I wouldn't say that clothes would make a character unique.
And your point is? Of course some people agree with you, just like others agree with me, that doesn't prove anything. That's a very poor argument. And for your second argument, what? I don't even understand what you want to point out.