This is quite a vague request. For once, RMXP already has a "One-Man Battle System", and that's the Default Battle System with only one actor. If you aren't satisfied with the position of the actor, get Tons of Add-Ons and turn Centered Battlers on or something.
You should be asking for specifics in a battle system you would want. The DW battle system is remarkably similar to the DBS anyway, so...yeah.