I'm doing a piss-easy challenge, beating the Weapons without spells of any kind. I'm saving it right before I fight them so I can do several different types of Weapon challenges on the same file, in progressively more difficult order. I'm going to use the 7777 trick on Emerald, because it's cheap and effective. I'll probably need it for Ruby, too. From what I gather, beating them without materia will require 99 Megalixirs.