A 995 motion is sometimes used to demurrer to a complaint (such as potentially in a med mj or other affirmative defense or where improperly filed due to jurisdiction) but more commonly used to challenge the validity of a count on an indictment or in most cases, an information after being held to answer for a felony.
Typically, if you get held to answer on several counts, but the defense feels some or all of the counts lacked the probable cause for the holding order, they will file a 995 motion and challenge specifically the probable case for those counts in hopes to have those counts dismissed.