Ruby Weapon? Are you insane. You dont even have to be there to win this fight.
Equip Cloud (or whoever) with the following
Ribbon (status effects nulled)
Knights of the Round linked with Hp absorb
Hades Materia
Master Counter linked with Mime
W-summon Materia
Before fight, kill off other 2 members, so that Ruby can not use sandstorm and remove your juiced character from battle.
The fight:
Doesnt matter who attacks first, Ruby cannot inflict status effects on you.
When it is your turn:
W-Summon Knights of the Round+Hades
What happens:
Ruby always counters KoTR with Ultima....HOWEVER, since you did W-summon, you will get to use Hades before he counters. Hades wil do crap damage, and all of his status effects will be resisted...except Stop. Ruby will be stopped, and thus cancel out his Ultima.
The rest of the fight:
Go have a sandwich, watch TV, whatever. You don't have to be present at all. When Ruby is no longer stopped, he will use a normal attack for about 700-1k dmg. You will counter with Mime..which is W-summon KoTR+Hades. KoTR will heal you to full, and Hades will begin the loop over again. After about 20-30 mins....you will win, without even being there.
The same general concept can be used for Emerald, however you need to be there for this fight as he cannot be stopped. Also, Airetam Storm does 1k dmg per materia equipped, so make sure no one has more than 9 (7 or less if you can).