You're putting Lich King, Malfurion, Sephiroth and Ganondorf against an supposed planet destroyer.
You then in the list include an entity that dwarf planets so much that it's ridiculous and is supposedly virtually indestructible in the sense that his body consist of energy 😛
Dark Khan lack feats adequate enough to pose a threat and I know nothing about Trance Kuja.
KOS-MOS has never destroyed one galaxy. Except in a noncanon "what-if" scenario, where she clashed with what is basically God in Xenosaga. Big guess who it is that caused the vast majority of the blast.
She has never shown that kind of power in the plotline to my knowledge.
Anyway, Dark Khan and Pyron completely wreck her with the utmost of ease, and she utterly annihilates the rest.