I hope that in the post-game rematches the trainers will have more diverse teams. Even in post-game Emerald they had a lot of the same Pokemon.
This I agree with.
Given the amount of Pokemon in the National Dex now, I'm kinda hoping they can get more diverse teams should rematches come back in these games. Duplicates are usually the reason that makes me not like some of these trainers as it's showing a lack of diversity.
I know certain trainers specialize in certain types which means they can end up having dupes but given we've seen Phoebe with a Dusknoir so far, the Hoenn Dex is getting expanded to include the 4th Gen cross-gen evos and maybe even a few more surprises given the Hoenn Dex was severely lacking in certain types, especially Ice and Ghost.