Today it was announced that the Pokémon Passimian and Oranguru will be available to download to Pokémon Sun and Moon and Ultra Sun and Ultra Moon through Pokémon Bank software for Nintendo 3DS. The Pokémon will each have their hidden ability; Passimian will have Defiant and Oranguru will have Symbiosis.
Pokémon Bank is the software for Nintendo 3DS that allows for Pokémon from 3DS games to be stored in the cloud and transferred to other games. Occasionally a Pokémon with its hidden ability will be given away through bank to reward players for paying the $4.99 per year subscription fee to use the software. Around this time last year the Alolan starter Pokemon with their hidden abilities were distributed through the software.
With Pokémon Sword and Shield versions coming later this year it is likely that Pokémon Bank will receive an update so that Pokémon can be sent to the new games when they release. This event is sure to remind and incentivize some players that may have let their subscriptions lapse to renew their access.