I just beat Ruby......I'm not saying it just to show off but I was very easy......I killed my two partners leaving Cloud alone in the fight......I equiped him with Mystile for armor and it doesn't matter what weapon you put.......When you beat Emerald remember you got the master summon materia?Well I equiped it and paired with MP Absorb materia........I put the W-Summon materia and I combined the Final Attack materia with Revive.......Then I got into battle.....First when you get into the fight with only Cloud Ruby's claws will be in the sand already then when the claws appear in your back.....Very fast summon KOR on the claws and then since you have W-Summon cast it again but now to Ruby.........Keep on doing that for about 5 times (remember you combined the master summon to Mp Absorb so you will never run out of MP)and Ruby will be out in no time.