He is at Mount Pyre
Underwater cavern.
you will find him underwater in a cave
You can get in after you beat Archie at the route 128 cavern.
he goes to his underwater hideout cave.
Through the magic of the final axe of the Egyptian Pokemon
Seafloor Cavern, just before you hit Route 129.
Archie is ez if you have grass types or electric types.
It is in the cave where Archie of Team Aqua tries to capture Kyogre. Alas you need HM Dive to get there.
After beating the game go to mt pyre and find the part where you got your orb Archie will be there and give you the orb now talk to the lady she will take them both from you.
You can find it in Archie's Base. Make sure to grab it, because there is no way to come back later and get it if you don't.
You find a Vulpix on the big tower west of Lilycove… You know, where Archie and T/A are.You can also catch Duskull, another good Pokemon. They are at about Level29-33.
Pokemon Ruby has Pokemon that Pokemon Sapphire does not and Pokemon Sapphire has Pokemon that Pokemon Ruby does not.