I only got ATK maxed on Dendro. The most important thing besides ATK with her is skill blooms. If her skill is at max, then only running 3 regular 1.2 skill act girls guarantees that she will double strike at 4.8 (or one Daisy, Viola, Cymbidium, future Hollyhock when she's bloomed, and others) Usually that is more than enough to wipe out the enemy by itself. If its not, then bring out the Kraken. DEF and HP are better used elsewhere like on counter and debuff girls IMHO.
She is a one trick pony, but its a hell of a trick
One more thing, Don't run Dendro and Kerria on the same team! Kerria needs everyone on her team to have skill act boost if possible...and it is