I feel like people think Sawyer was a complete noob when we first saw him, but i do think he had a bit more experience than we give him credit for, as he did travel Hoenn for a bit and even got badges from both regions. Granted he was still pretty much Ash's "apprentice", but that had more to do with Ash having more experience than Sawyer having none.
I find that his personality and growth made him a really endearing and interesting character to watch, but that these aspects of him get often overlooked compared to how his battle was nicely animated.
As for Barry, he might not have been much of a threat (like, at all), but i found him really funny and not annoying at all.
Also, i think Conway was a better rival than a lot of the main rivals Ash had in this show, despite them not giving him much focus. I wish the show had more cunning characters like him.
I truly like Gary as a character but i didn't think his battles with Ash were all that great.
Gladion didn't really feel unique to me and the fact that we didn't often see him battling other characters besides Ash makes it really hard to attest how strong he actually was, compared to Alain whom we often saw going against legendaries and E4 members (therefore, he felt as a way bigger threat), tho i do think both of them were unnecessarily edgy sometimes. Paul could be unnecessarily edgy too but at least that was often played as a joke, which made wachting him feel less boring (tho i do have my grips with them not having him show a *little bit* more humanity as i think that would make him feel less one-dimensional).