Personally, i think that the Emerald versions of the Hoenn Gym Leaders were way better than the RS and sadly the ORAS (ehemcopypaste) versions of their lineups.
In Emerald, the hardest to beat, relative by the time the player had to face, was arguably Brawly. If a player didn't catch any good Flying types in their journey, Brawly's Leer Spamming Machop would make good way for Brawly's ace Makuhita to laugh at. It would use Bulk up when it had the chance and if your Leer'd pokemon still insisted on fighting it, he'd just go Vital Throw along with the Boosts it got from Bulk Up, and the shredded defense from the Machop's Leer. If the player didn't know that a Wingull with Wing Attack was the best choice to use against Brawly's team, there was high chances that someone would have gotten Swept by Makuhita's Bulk-Throw combo. Even a Tailow would get One shotted by a Bulk up Vital Throw because of the neutral damage it takes as a flying type to Fight type moves. Lets remember, Vital Throw has a BP of 60 + STAB, which is really high that early in the game when most of your mons have moves with the BP of 40 or less. The level spike between Roxanne and Brawly is really large as well.
As for Normal in Emerald, I found his revised lineup to be more enjoyable to take on against. Instead of his classic RS version of just using 2 Slackings and a Vigoroth, his Emerald team had a lot more variety on it. His Spinda has some really good moves such as status effects, his Lineoone is great at annoying leads, and of course his Slacking with its Facade was just as awesome as it would OHKO mons that didn't resist the boosted Facade damage.
Another of Emerald's awesome lineups was for Tate and Liza, which i've said previously, is my favorite gym battle to be ever introduced in the core series. As i also said previously, it was sad to not see the Emerald version of Tate and Liza's lineup in ORAS. Having the epic battle against the awesome synergy of Claydol and Xatu in 3d would have been an extremely good experience.