What's a good level to be at for the Crypt in the swamp?

What's a good level to be at to kill that demon in the Crypt? Sarah is LVL 20, Random is LVL 22, & Guandia is LVL 22. I tried it once but had to go back to a previous save because like Harlow to weak. God he hit Random for over a 100. And I tried to switch to using Sparks but can't Why?
Baretta seems to be more of a cheerleader not fighter. Or is there a tactic with her? Once I get her and before we go into the Crypt can I level her or something? Thanks in advance.
