remake/sequel means the elite 4 will have updated rooms, meaning no more bland looking rooms! Imagine drake sitting on a chair with a harpoon on the back of the ship accepting your challenge.
pre elite 4
Sidney- Absol, Crawdaunt, Shiftry, Mightyena, and Cacturne
Phoebe- Banette, Dusclops, Sableye, Dusclops, and Banette
Glacia- Walrein, Sealeo, Sealo, Glalie, and Glalie
Drake- Shelgon, Salamence, Flygon, Altaria, and Kingdra
(interesting, Sidney and Drake only had different teams between RS and Emerald.)
post elite 4
Sidney- Absol (mega evolve) Crawdaunt, Shiftry, Mightyena, Cacturne, and Mandibuzz (though there is Umbreon, Zoroark, and Honchkrow that could replace the others like Shiftry or Crawdaunt.)
Phoebe- Banette (mega evolve), Dusknoir, Mismagius, Chandelure, Trevenant (could use some work)
Glacia- Walrein, Glalie, Frosloss, Glaceon, Mamoswine, Weavile. (or Abomasnow for mega)
Drake- Flygon, Salamence, Haxorus, Hydreigon, Kingdra, Garchomp (mega)