Its kind of funny how Ash's character is slightly altered based on which female companion is traveling with him.
Misty: Ash was portrayed as immature, a newbie and an idiot, but this all made sense since Ash was a beginning trainer at the time. So its understandable
May: Ash is portrayed as more mature and competent around May, but he still had a temper and lost his patience often. Ash in Hoenn was like a mix of what he was in Kanto/Johto and what he'd eventually become in DP. I also like how Hoenn is the first time Ash actually tries to help one of his female companions who is just a beginner for the first time. Ash still loses his patience with May sometimes and they argue a bit but less than Ash/Misty. Ash is more or less portrayed as a big brother to May, similar to what Brock was to Ash.
Dawn: Ash is portrayed as very mature and competent, Dawn is almost treated like his twin sister or something. Most of Ash's anger in this series is directed to Paul or Hunter J. Ash and Dawn argue a little bit, but not as much as past girls. He also trains with Dawn a lot more than any other character.
Iris: Ash becomes an idiot again for no reason. Iris constantly mocks him and calls him a kid. Ash is reset for the first time and loses most of his skill from DP and prior. Iris is viewed as Ash's superior the entire saga.
Serena: To Serena, Ash is her knight in shining armor. All of a sudden Ash is mature, competent and heroic again, and Serena thinks he's amazing and that he can do no wrong. Serena practically worships the ground Ash walks on, and to this day she's never had an argument with him. Even May and Dawn called Ash out several times when he was doing something stupid or bickered with him, but Serena doesn't do any of that because she idolizes him. She practically admits to wanting to be his wife. Bonnie/Clemont are also amazed by Ash as well.
Its rather funny that depending on what character trope the writers give the female who travels with him, Ash's character has to be altered to fit whatever female lead he's with. For example Kanto or BW Ash wouldn't work with Serena. If Serena saw how Ash was when he was a rookie she probably wouldn't even like him.