It's kinda weird, I guess maybe they've lost investment in the female characters (they made a token effort for Lillie, but likely for the reason she was THE SM story character, they couldn't get away with not using her). Or maybe they realised the male companions kept getting the shaft and decided to give them a fair turn.
Concerning battling, I always had this theory that someone in charge complained about the more vicious TR battles in BW/early XY and said to tone down the cuter/feminine characters getting roughed up. It would explain the awkwardness of them always trying to call off Serena's battles when it was inevitable she'd get her ass kicked, and why SM pushed far more for non-battle agendas and scenarios (and why Lana, despite being the 'battler girl' actually did ZERO trainer battles). They can still battle TR and other baddies plenty times, but of course TR were toned back down to curbstomp material around that point too.
There's a strange consistent pattern post-BW in that the girls all officially lose ONE battle each, it's weird, like if someone DID make that mandate they added 'Oh fine, they can get kicked around ONCE just to tone down the plot armour'. SM certainly timed that event methodically if so, though Journeys would suggest they just couldn't tweak the formula enough to make the girls interesting otherwise. They tried some more unique agendas and stories but after a while it just comes back to battling.
Granted Ash was also the ultimate clown in SM, as were his team, it was hard to compete in terms of gags and slapstick with him, and he would inevitably get the best battles even if the others DID do them. There were many occasions they overused Ash but I think more because he was far more game for it than the other characters, who sometimes struggled to establish a core to work off of.