You mastered KotR and didn't master W-Summon? HehOriginally Posted by Giga Guess
You shouldn't need to use W-Item for this battle. W-Summon, Hades, KotR, and Mime are really all you need. Well, Revive-All(or Phoenix, though that uses more MP), to revive the two characters you killed before the battle. After that, it's pretty straight forward.
Or, just use dazers to paralyze Ruby, as one person suggested. W-Item would help to use two items at once(could paralyze and heal in same turn), but you don't need to use the glitch with it. Then, just W-Summon KotR and then mime it. Shouldn't be too hard.