As far as I can remember, the only Theme that cannot be used in VS/Events is Mental might. The only you cannot use in Trainer challenge is Ralling Cry.
All the rest, at least the ones can be gotten now by new accounts, can be used in thrice Trainer challenge, VS and Events, and Daily challenges.
Did you already won 7 games in the Trainer challenge with the Fire, Lighting and Water beginner decks (Born of fire, Crushing current and Hidden depths) to complete'em? That's the condition to unlock'em and play'em in VS/Events, in Theme VS or Theme Event modes only of course. Same if your beginner starter decks would be XY basic Red, XY Basic Yellow and XY Basic Blue whom are older.
You can copy the decks to play it in Standard/Expanded/Legacy. But normal would be being destroyed against Meta decks.
More than that, you can use any bought in shop deck everywhere in the game, again, in THEME mode.
About the Daily challenge, if you have to KO pokémon with your fire ones, won't work playing Mach strike or Iron tide to complete ir. They are not fire pokémon in there, but I don't think that's the issue.
Did I hit the nail? If not, is there any example you can give us of what is not working with the name of the decks and the mode you're trying to play?
Edited by Chasista, 05 January 2019 - 03:25 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/