All canon Metal Gears, does not include any outside of the Kojima games. (Ex of not included: MG RAXA)
Only weapons that would fall under nuclear warfare are counted for this list, i.e. launches nukes or takes down nuke-launching gears, as that is the definition of a true Metal Gear. (Ex of not included: MG EXCELSUS)
The games the gears appear in are listed as hints.