In misty's gym look in the box looking pool swim and keep pressing
A.
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Find the machine part in the cerulean city gym give that to the guy.
In pokemon gold you have to find first an itemfinder. Then go to the centre of the cerulean gym where there is a square type water is held. Surf in the water until you get the machine part. I know it would take time but believe me you will get there only.
I hear you can trade from crystal to sapphire. You have to have two gameboy advances, a gba link cable, and in crystal you have to go to the time machine.
After you get the part go to the Power Plant and give it to the guy near the machine
you catch it at night