Ash is the main character so at the end of the day he will always get the most/better screentime of the cast. No matter how much I dislike seeing it. It's a the number one reason I'm glad characters like Calem, Brendan, Lucas, Ethan, and Hilbert don't make it on to the anime, much less the main cast. And while I have accepted it, I wish they wouldn't undermine the other characters in the process. Clemont, Bonnie, and Serena are usually background/captured in filler episodes where they themselves are not the stars. Like the examples give of the Spewpa and Pancham episodes. I don't see why Clemont or Serena couldn't have been the hero of one of those episodes. Even in Serena's own episode about the Rhyhorn racing, half of it was split between her and Ash.
I like the Kalos main cast. All the new characters are entertaining when they are allowed the focus. But it feels like the writers are trying to make sure nobody becomes a real breakthrough star long term. As much as I love Clemont, I wonder how much he's going to get after he loses to Ash? Serena, despite being a playable character like May and Dawn, suffers from a lack of focus, and screentime. I feel like there's still so much I don't know about the character besides her stance on racing and her crush. And we're like almost 15 episodes in.