Rustoboro City is the first big city in Hoenn. This city features a variety of homes and important buildings. Most notably is Devon Corporation's headquarters which is where you need to go to revive Fossils.

Trainer School
The city is also home to the Pokémon Trainer School of Hoenn where characters will teach the basics of battling.

Gym
The Rustboro City Gym is the first Gym in Hoenn and doesn't feature a massive pzuzle. This gym has got a few trainers in who are, in Ruby & Sapphire, bypassable through a path or in Emerald, interspersed throughout a small maze which gives two possible ways of travel and bypassable as well. At the end is the Rock-type Gym Leader, Roaxanne, who will give the Stone Badge when defeated as well as TM39, Rock Tomb.