I'm playing Pokémon Emerald for those nostalgic feels, but wanted to find the Dragon Fang item. The only way to do this in Hoenn is to rematch a Dragon Tamer in Meteor Falls. On the fourth+ rematches, his Shelgon will hold a Dragon Fang to steal using Thief. I've been able to rematch him once so far quite easily, but after that, he doesn't seem to want a rematch at all, even with a LightningRod Pokémon in my party. I read on Bulbapedia that
In Pokémon Ruby, Sapphire, and Emerald, the PokéNav's Trainer's Eyes or Match Call has similar functions to the Pokégear, keeping track of Trainers who eventually want to re-battle the player. In Pokémon Omega Ruby and Alpha Sapphire, the Trainer's Eye function returns, and Trainers are ready for a rematch more frequently than in Generation III; in these games, the Trainers' teams improve as the player progresses through the game, and are at their strongest after the player has entered the Hall of Fame.
This should mean that this rule only applies to ORAS and not the Gen III games, correct? In that case, you should be able to rematch trainers as many times as you want to before the Elite Four, but there has been nearly a 1-hour (and ongoing) gap between my easily-obtained first rematch and the second one, which I'm still trying to get. The Dragon Tamer's Pokémon go as high as lv. 49 when he finally has the Dragon Claw, which is higher then some of the first Elite Four's Pokémon--seems a little suspicious that I could battle him with those powerful Pokémon before the Hall of Fame.
Anyway, thanks for reading and I hope you'll answer!