Kid Icarus Uprising has an embarrassment of riches where boss characters are concerned. For Palutena's Temple, imagine the Chaos Kin appearing at random, skittering around the stage and possessing any player it can snatch, while the other players try to get the final hit on the Kin and self-destruct it.
I'd personally love to see Hewdraw in that stage. It could fly above the stage raining down fire and lightning and ice, and dealing enough damage to it will cause one of its heads to fall to the ground, bouncing through the dungeons and caverns and such until someone finally takes it down.