No. No no no no noooooo. I hold up The Legend of Zelda: Breath of the Wild - or more specifically, Zelda herself - as a prime example of why Nintendo games should NOT have voice acting. Going back a little further, there's also Metroid Prime 3: Corruption as another great example. Pick any Fire Emblem title from Awakening onwards as another example. The thing of it is that these were all made by developers with more capability than Game Freak and they're all terrible quality. They all significantly detract from the experience.
I'd rather they put the money that giving these games voice acting would cost into actually making a decent product tbh. There are so many things wrong with Pokemon that need to be fixed that something like voice acting is pretty unimportant really, nice as it would be to have if it was done properly...but nothing about Pokemon is done properly, so there's no reason to believe the voice acting would be any different. I can't argue that some cutscenes in the later games would have more impact if they had voices behind them (although whether this would be positive or not is another matter entirely) but a lot of Pokemon's "story" events and dialogue doesn't happen inside cutscenes, and the contrast between full voice acting and silence would be even more jarring than the utter silence we have now. Or worse, stock phrases and grunts, gasps, laughs, and other noises.
You can bet that the majority of the dialogue would not be spoken in a project like this, which is another reason why I'd say it'd be a terrible idea. It'd need to be done in multiple languages and the cost, time, and resources for such a project would be astronomical. Pokemon is already under staffed and under budget, allocating more of the already sparse budget into hiring mediocre voice actors to record one or two lines of dialogue that the characters repeat over and over and OVER would come with further costs to the gameplay, and I think we've already sacrificed enough with Sword and Shield to have it cut down even further.