Is anyone else disappointed with the amount of trainers you can re-battle in not just ORAS, but gen 6 as a whole? Its disappointing after the amount of memorable characters you could rematch in Gen 5. In Black/White 2 you could rematch; Your Rival, Cynthia, Those two Gamefreak employees, Cheren, Bianca, The Shadow Triad, The Striaton leaders, All the Gym leaders, Benga and Corvus.
X and Y only had Serena and Emma. Hell, the Elite 4 didn't even get stronger. ORAS at least makes the elite 4 stronger, but you can't even re-battle your rival. You can re-battle Wally, but only after defeating one of the Maison leader people. There are also those extremely unmemorable trainers from the Battle resort. I mean, back in X and Y did Gamefreak just forget you had 3 more friend characters? It would have also been nice to be able to rematch Sycamore.
I also wanna know why you can't re-battle the gym leaders in ORAS. Doesn't Gamefreak understand we want that by now? Just my 2 cents on the matter.
In X/Y the gym leaders, elite four, and champion all show up in the Battle Chateau (On route 7, just past the daycare) with considerably more powerful teams. But they require that you level up your ranking. Diantha can't even be rebateled until you reach the highest rank.
In ORAS, there are NPC trainers on every route except 101 that can be rebattled, over, and over, and over. Their teams expand with additional pokemon once you beat Groudon/Kyogre (or the E4, can't remember which), and they keep leveling up until they hit somewhere around level 50. Additionally, you can rebattle the E4/champion as many times as you wish, and their teams get a significant boost after the first time. Not to mention all the Secret Base people you can rebattle daily. So there is far from a shortage compared to X/Y.
That said, I do agree that it would have been fun to rebattle the gym leaders again, and there are hints that it should have been possible at one time (Roxanne specifically mentions that she'd like to battle you again if you talk to her after the Delta Episode, but there is no way to initiate the battle). Unfortunately I think that said battles where cut at the last minute.
There are also hints that the Gym Leaders would have had quests for you after the E4/Groudon/Kyogre, but only Wattsons was kept (I think in part because it was a memorable part of the originals). For example, if you visit the Fossil Maniac after the Delta Episode, you will see him have a heated discussion with Roxanne ending with her running away in tears because he doesn't want to give her a fossil. Then if you go and talk to her in her gym, she is her old chipper self. It would have been nice to be able to donate a fossil to her, I mean what else am I going to do with the 30+ fossils I've accumulated from Mirage Islands. >.<
Still, it feels like something is missing, and I am afraid that something was cut to make a deadline. Hopefully we will get both an Emerald and a Z game in the future that fixes this.