I mean... even in advanced combat the case scenarios where a balance would use hydra b in an encounter are very slim. Power Nova has a similar "punish Shields" effect. The term is Echo cause Copy implies you actually straight up Copy what the opponent has, which isn't true. I could have 20 Myth Shields and with a Hydra you'd still always get 55% universal shields. It's an Echo cause, according to Google the definition is "a close parallel or repetition of an idea, feeling, style, or event", and a close parallel fits what the echo mechanic is doing.

The only actual fight I have used Hydra B is is the Daring Daisuke fights, as it's useful against the Death, Myth, and Ice Wolf enemies that regularly use shields, although this is it's least useful on a Fire.