No judgment without a defense shall be entered against a party then a minor, or confined in a penitentiary, reformatory or any state hospital for the mentally ill, or one adjudged incompetent, or whose physician certifies to the court that the party appears to be mentally incapable of conducting a defense. Such defense shall be by guardian ad litem; but the conservator (and if there is no conservator, the guardian) of a ward or the attorney appearing for a competent party may defend unless the proceeding was brought by or on behalf of such fiduciary or unless the court supersedes such fiduciary by a guardian ad litem appointed in the ward’s interest.