Oxy is very powerful, has skill activation and AoE.
I still rock her in my Team 2 which is composed of 6* simply due to her having the Skill act, and the pre-Bloom 6* (especially the older ones, which changes with Burning Bush and forth) do not.
Plus her personality is adorable. She acts all tough and strong in combat, but when you click her for the quotes, plus her H scene, she is very soft spoken, and melts quickly (mofu fu fu :3)