You have 5 uses of mode gauge reduction available from the start with that team. Whacking her a few times will get her back to raging extremely fast so you have no methods of recharging them. They will run out extremely quickly and the team will degrade to uselessness. A team that does high damage can stun a union boss just by attacking twice.
Raid healing & buffs don't actually work; even if they did, your teammates might not want to use Andromeda.