You will first meet
Celio when you travel to the
Sevii Islands with
Bill after defeating the
Cinnabar Island Gym. Celio is a lot like Bill in a number of ways, being a very creative inventor. When you first meet Celio, he will ask that you run an errand for him, officially activating the
Lostelle Mini Story across the first three Sevii Islands. However, Celio's main purpose in the game will be found after defeating the
Main Story and obtaining the
National Pokedex.
The
Post Game Story revolves around both
Celio and
Team Rocket as you travel throughout all seven of the
Sevii Islands. The goal will be to obtain both the
Ruby and
Sapphire so Celio can finish his Machine on
One Island, which will take traveling through all the Sevii Islands and defeating Team Rocket once and for all in order to do. Once you have retrieved both the Ruby and Sapphire to Celio, he will complete his machine and thus will allow you to connect
Wirelessly with trainers playing
Pokemon Emerald in the Union Room.