when i killed ruby and emerald earlier today i more or less used just cloud on level 96 to kill them.

i walked into ruby with clouds ultimate weapon an escort guard armour and a ribbon. i had barret and cid in KO status before i walked into the fight.

for ruby :

have nights of round linked to hp absorb then have mimic haste and w-sum ability on cloud also a maxed out hp plus materia is good just take cloud in with that set up while other 2 characters are in KO status.

i had to use omnislash to get rid of the tentacles then i casted haste then i done w-sum with knights of round on ruby and had cloud mimic it.

each time knights of round hit i got 9999 hp back on cloud so all i had to do was keep him using mimic each time.

mimic command casted knights of round twice each time.
ruby went bye bye.....

had knights of round at level 2 for emerald.

i more or less done the same thing with emerald cept i went into emerald battle with all guys at full health and had barret cast haste on cloud then i ignored the other 2 characters an done the same stuff with cloud again and emerald soon went bye bye as well