Regarding the cavalry classes, yeah. That being said:
Can you list some examples? I’m legitimately curious who you actually think fits better for this role that is a 4* unit or below, aside from Ridertoki. Just because everyone deals 2x damage against Berserkers, that doesn’t mean there isn’t a relative spectrum where some are going to do it a lot better than others.
Berserkers are often best dealt with quickly, and there’s no better way to manage this than either with a strong single-target NP that will delete them. The only place this proves to be a problem is maybe if there are Break Bars at play, but even then, Mecha Eli performs pretty well against the likes of Megalos. A Buster NP Brave chain from her is decimating, even in spite of the two-hit Buster card.
I wouldn’t even just call her a Berserker “specialist”, but in reality any unit with a strong 2x NP is going to be excellent for taking them down. What is it really that you think defines a specialist? Does it need to be the critical potential of Jalter? If that’s the case, then the list is awfully short.