Yunalesca.

[Jyunichi]

To be fair when you get to omega weapon all the training you already have done since the fight with yunalesca would have greatly enhanced your party.
more magic more techniques. take everything you had when you fought yunalesca and fight omega and his dungeon of badies. especially the stone things.
and for the magority. summoning is just a cheap way of winning. i dislike summoning in any and all final fantasy games. using strategy is what these games are all about.
but anyway. yunalesca i never died once on her. quick hit wins in most battles. especially when combined with haste and trio of 9999

 

[Gert]

I agree with someone else who said that the emotional element really includes everything leading up to the fight... The whole walk through the Dome is just so epic and emotional, seeing the past with the pyreflies, and

Spoiler

Auron's demise

. The entire thing was just touching, emotional, painful, and above all shocking, all at once. Probably up there in FF game "" moments.