Feel free to download these files and then copy and paste their text these into a custom meta to quickly import opponents. Note that these files may not be perfectly up-to-date with the standard metas in the app, although they are intended to be the same.
For more accurate results, I recommend logging opponents you actually face, rather than importing them from this page. Using these imports is efficient, but doing so will not allow you to make use of the Meta Filter and Time Range utilities, and will not create an accurate representation of the opponents you face. You can learn more about the recommended uses of custom metas here.