you find him on one island in a building with a pokeball on it and a red roof.
You find the ruby and give it to celio
beat the elite four
You also find the sapphire and give them both to Celio.
You can find it at the six island after you get a rainbow ticket from Celio when you give him the ruby from mt.ember when you catch 60 or more pokemon.
Hes bills friend on island 1
Celio is the man standing right by the giant machine in the One Island Pokemon Center you can't miss him.
He is on 1 island in the Pokemon center building in front of the huge machine
celio is on the first island you can go there after you win at the cinabar gym, bill will be wating for you outside the gym
to get to ruin valley on Pokemon leafgreen you have to get the ruby in mt. Ember and bring it back to celio then go to six island
you find every single Pokemon and then you go to her and then you ask twice and she will gve you three moon stones, five fire, and two sun.
there is no cecilio,,, celio only,,, you can find him in the johto region,,,
You can find mewtwo in cerulean cave after you beat the elite four anf found both jewels for celio on one island