https://www.gamespot.com/articles/pokemon-new-free-legendaries-for-august-2018-avail/1100-6460839/

A new month is upon us, which means another pair of free Legendary Pokemon are now available for Ultra Sun and Ultra Moon. This time, The Pokemon Company is giving away the Ruby and Sapphire cover monsters Groudon and Kyogre as part of its ongoing Year of Legendary Pokemon promotion, but as usual, you'll only have a limited time to grab them.

As with previous distributions, the way to receive the Legendaries depends on which region you live in. Once again, US residents will need to travel to a specific retailer to pick up a free download code for the Pokemon. This time, the code will be available at participating GameStop stores from August 3-26. Pokemon fansite Serebii reports that players in the UK will need to travel to Game stores to get the code.