Steven is the son of Mr. Stone, the creator of the PokéNav. Like Cynthia in the Generation IV games, Steven is found throughout the game, giving items and tips to the player throughout the game.
Pokémon Emerald
Unlike in Pokémon Ruby/Sapphire, Steven is not the Champion of the Pokémon League in Emerald Version . He is found in Meteor Falls after you became the Champion of the Pokémon League for the first time. You can battle with Steven there, but he is much stronger. He is merciless and has many strong Pokémon. You can only battle him once, unlike in Ruby and Sapphire.