Knights of round
Definetely.
Yes.
Yes.
Yes.
Yes.
Yes.
Yes it could but not in one hit.
Knights of the Round summon from FFVII as it does the most damage any summon will ever do if it's maxed out doing 13x 9999 damage.
Either but i would say Knights of a round, for damage reasons even though it takes forever to charge.
No because there are 13 Knights verses one Eden you can only guess what happens to Eden!
Yes, nothing else will do. You cannot reach the island in which it is kept any other way. However you can defeat Emerald Weapon and trade the Earth Harp you receive to a man in Kalm, and he will give you three Master Materia, the summon one will allow you to cast Knights of the Round, though you won't have a separate Knights of the Round materia.