To spawn anything at all you first need to enable cheats. Host a private battle and type
!cheats
The Luarules version will
not give the inaccessible units.
/give all is likely to explode stuff and will be filled with a lot of chaff (50 versions of each com chassis etc.).
The safest way is to spawn units individually.
You can see most units listed
here. Check the inside of the file for the usual name (armpw.lua -> Glaive). To spawn the unit, use the /give command with the file name, for example when the file is called
hoversonic.lua
then you can spawn the relevant unit with the command
/give hoversonic
Note: this will not show some mission-exclusive ones (like orbital bombardment) or customized ones (for example mission Sunlance is different to the spawnable MP one).