In addition to the infinitely reusable TMs the games introduce new moves like Scald and Acrobatics that can lead to interesting new strategies like using Swagger then exploiting the opponent's greatly raised Atk stat to nail them with Foul Play.
Now for the things that irked me. I greatly disliked how the game tries oh so hard to shill for those damn elemental monkeys. You're basically forced to use them to beat the first gym and they show up irritatingly often during the adventure despite being butt-ugly to look at.
There's also the reduced exp you gain from fighting weaker mons which sucks if you're going for some grinding.
Finally, some of the best mons evolve way too late, including Larvesta evolving at level 59, which essentially locks it and other mons like Hydreigon to the postgame.