Would it be possible to have a mode in quickplay and career to play exclusively with thematic decks? Theme Deck (TCG) - Bulbapedia, the community-driven Pokémon encyclopedia (bulbagarden.net)
You should be able to select the period, so that you can play for example only with neo decks against other neo decks, or only with gym decks against gym. More experienced people can advise whether it is okay to play in mixed mode as well (basic decks vs. rocket, gym decks vs. neo…etc…). I do not have the expertise to make correct decisions on this.
I think this mode is much more fun because it levels the difficulty to both players