[QUOTE=lionhearted]
Personally, I would wait til I could move around in Balamb Garden because the Adamantoises only appear once every time you enter the area of Long Horn Island. Therefore if you enter it with the Balamb Garden, you could fight them then quickly get on and get off the Garden and fight them again rather than walk alll the way back! That's my preference. QUOTE]

Yes this is the place to find Adamantoises. However, I just kept runing around the southern beach closest to mainland on Longhorn Island, and never once had to leave and come back, or enter and exit Balamb Garden. It only took a few battles with Adamantoises to get enough adamantine for the ultimate weapons that required it.