Here is a good write-up on Laeva (view in google translated)
https://fukoto.com/flower-knight-gir...-laeva-matome/
Its not what I used,but seems to fit more of what you got. Try to end the 3rd fight with a Purple weakness crit slam.
Hydrangea will be more useful when you get her maxed out, very versatile girl.
Always use taunt FM on her to get the skill act benefit.