Currently the only ways to test Prerelease cards for Genesys format is to play in TCG casual queue or set up unlimited duels, both of which are highly problematic for different reasons.
Decks with Prerelease cards could have their point ceiling lowered to account for the fact that some future cards might be getting points?
This was something discussed when we released Genesys queues, and we decided not to allow pre-release cards, as that simply defeats the purpose of Genesys, since people could then queue up with any new, dominant archetype in the OCG before it releases in the tcg and gets points.
Since that would give a significant advantage over other Genesys players, we decided not to do it.
Additionally, with the OCG adopting the Genesys format, they have ruled that cards not released in the TCG will not be allowed. This directly supports the idea that only cards the TCG has been able to evaluate and apply points to should be allowed.