As of 08-Apr-YC123 Mercenary enemies found in this mission have Shields weak on EM damage and Armor weak on Explosive damage. By that time, recommendation to deal Kinetic and Thermal damage (on the main page) is vastly misleading !
Number of BSs not correct
BTW, I did this mission on 08-Apr-YC123 and counted 7x Battleships Mercenary Overlord in first pocket. I can not say from which group they were 4x.