Above answers are good suggestions. Try following what keithcurtis said, first. If more is needed beyond that, try Finderski's API suggestion method. To help clarify what happens in roll20: 1. Just because the GM sees the monster name, does not mean the Players necessarily are seeing it. Things can be shown to GM/Token-Controlling-Person that are hidden from others who don't have control of that token/chracter. 2. SHOW NAMEPLATE (a checkbox on each individual Token settings) determines whether the Name shows underneath the token on the map page (to those who have permissions to see names). 3. Token Settings > Advanced Tab > has the checkboxes to control whether Everyone, No One, or Only the Controlling Player & GM, can see the Nameplate. If #3 is set on SHOW NAME: SEE & EDIT.... that means players and GM can see the nameplate if it is showing. If #3 is set on SHOWNAME: EDIT ONLY.... that means only the GM and controlling player can see it. It's hidden from the other players. If Show Nameplate is unchecked on the main Token settings of that token, it can still have a name, but the name doesn't show on the map. It can still show in the Turn Order, still dependent upon your settings in #3, with the same provisios.
