The Regionals promo for the Unified Minds quarter will be an alternate art version of Lillie from Sun and Moon!
The artwork originates from the Japanese Sky Legend set, which was released in Japan on April 26th.
Several Trainer cards have been getting alternate art reprints in recent Japanese sets. It seems they will be used for Play! Pokemon promos, such as Pokemon Leagues.
Thanks goes to @JOKMOK_events for the picture!