In Co-op mode, Flying Castle's REC stat is increased from 6 to 7, due to its base ATK of +1. Flying Castle's passive does not visibly change; however, there are some situations where Flying Castle is allowed to counterattack in spite of its passive.
Flying Castle's Hyper, Immovable Object, does not visibly change in Co-op, but has a slightly different effect. The Hyper will only force enemies (and not other players) to battle the player, but otherwise functions the same as in Normal mode.
Flying Castle's passive and Hyper are unchanged in Bounty Hunt mode.
Flying Castle's base stats give it 34 starting stars and a markup of +15% at shops.