Swords bounce off his skin , magic will only work once, flash steps will be evolved around. They could possibly attempt to contain him but then considering Ichigo escaped from the toughest spell.....
Ichigo escaped from the toughest spell?
Theoretically they could win by imprisoning him with a stronger form of their dimensional boxes(given enough prep time) I suppose if they used the soul ejector the very first time and then stuck him in one of Urahara's gigai's IMMEDIATELY, but yes basically they're screwed. Also of those tactics require time and that's a luxury they don't have. Does H/P doomday evlove during combat or only once he's been killed? Also what was his base level?
He wa evolving like on the fly,superman was flying so he evolved ranged poison bone stingers and lightning breathe ect,and his base level was enough to take on a superman using a motherbox.