Legal Question in Business Law in California

I don't see anything illegal about this, on its face. If the Motion to Compel is on behalf of someone representing themselves without an attorney, then the attorney filing the motion will have to enter an appearance on a general or a special basis and this would have to be done with full agreement and meeting of the minds between attorney and client. If the attorney is filing something that the attorney is already on record as being the counsel of record on the case and has employed a paralegal or other assistant to help prepare the motion, then that is all right so long as it is done with the attorney's full supervision and review and so long as the payment is not done in violation of the professional ethics rules relating to sharing fees with non-attorneys.

There is nothing necessarily illegal about the process you describe. Anyone can write a motion. It must be signed, however, by the party making the motion, or by an attorney of record representing that party as a client. The motion must then be served on the other parties, and this can be done by any adult nonparty. Finally, delivery of the motion to the court clerk can be done by anyone.

No more so than a paralegal or clerk in his office preparing it, as is frequently done, as long as the attorney is the one responsible on the record.