The help text for pokedex dump -l says

  -l LANGS, --langs LANGS
                        comma-separated list of language codes to load,
                        'none', or 'all' (default: en)

However, the values 'none' and 'all' don't work (they are treated as language names) and the default is to dump all languages, not just English.

We should either make it work the way it says it does or fix the documentation.