In Co-op mode, Kae's stats and passive do not change.
Kae's Hyper, Blazing!, has a different effect in Co-op. The Blazing! stock effect granted by the Hyper only affects players, has a duration of 2 chapters instead of 3 chapters, and does not grant -1 DEF per stack unless the affected unit is Kae. (In all other aspects, this Hyper functions similarly to its Normal mode counterpart.)
Kae's passive and Hyper are unchanged in Bounty Hunt mode.
Kae's base stats give her 40 starting stars and a price adjustment of 0% at shops.