Starting theme decks are Online exclusive. they are given to you "incomplete" and they change cards little by little through 7 wins to give you the final upgraded deck.
The in-game shops theme decks on the other side are IRL theme decks that come exactly as they are. No changes to upgrade. But as told, they give other rewards, coins and a pack when 12 different trainers beaten.
That said, I recommend you to get Mach strike and Imperial command from shop as they are the 2 best Theme out there, and to get some standard cards, also both from Forbidden light.
Edited by Chasista, 28 May 2018 - 12:36 PM.
WE WANT LEGACY TOURNAMENTS BACK !!! If you also want it, show your support http://forums.pokemontcg.com/topic/55966-feedback-making-it-easier-to-get-the-cards-you-want/
5th day reward packs list http://forums.pokemontcg.com/topic/56679-5th-day-log-in-pack-is-random-got-a-gur-dd/?p=593037
Foro en español, también existe: http://forums.pokemontcg.com/forum/2-español/