Volarmis> My strategy is simple. I send my best devensive core (the one I use as helper team) to scrap as much damages as I can. Then I send my Counter+Crit team based on Pink Miko + Easter Cactus for resurection + Counter&Crit girls to scrap even more damages with Counter. Then, if needed, I finish with my best Crit teams.
For the firsts battles, defense, evasion and counter are the key, unless you're able to one shot them.

Here is my Laeva clear: